Access the full text.
Sign up today, get DeepDyve free for 14 days.
Loading next page...
/lp/wiley/characterization-of-soil-nematode-community-structure-in-semi-arid-OUoB0TiAE0
- Publisher
- Wiley
- Copyright
- © 2022 Crop Science Society of America and American Society of Agronomy.
- eISSN
- 2639-6696
- DOI
- 10.1002/agg2.20277
- Publisher site
- See Article on Publisher Site
Abstract
AbbreviationsCARCCentral Agricultural Research Centercpcolonizer persisterEIEnrichment IndexMIMaturity IndexNGPnorthern Great PlainsPPNplant parasitic nematodeSIStructure IndexSOMsoil organic matterINTRODUCTIONNematodes are a diverse and highly speciated group in the soil environment. Occupying multiple trophic levels, these organisms can provide insights into the structure and function of the soil food web (Neher, 2001; Ritz & Trudgill, 1999). Broadly, nematodes can be grouped into five major trophic groups: bacterivores, fungivores, plant parasitic nematodes (PPNs), predators, and omnivores (Yeates et al., 1993). Plant parasitic nematodes are primary consumers, affecting soil food web resources through direct herbivory. Bacterivore and fungivore nematodes graze on decomposer microbes, thus contributing to soil nutrient pools, while predatory and omnivorous nematodes regulate the soil food web by preying on other nematodes and invertebrates in the soil (Ferris & Bongers, 2006; Ferris & Matute, 2003).Ecological indices are a way to quantify community connections, often focusing on the number and prevalence of various trophic groups and genera based on a colonizer‐persister (cp) scale defined by life‐history strategies, food sources, and nematode responses to soil disturbance (Bongers, 1990; Bongers et al., 1995). After being assigned a cp value, nematodes are assigned to trophic groups (defined by feeding habits) (Bongers & Bongers, 1998). Together cp value and trophic group determine functional guilds (Ferris et al., 2001). The Structure Index (SI),which increases with disturbance, is a measure of soil food web stability as affected by disturbance, while the Enrichment Index (EI) increases as the abundance of opportunistic bacterivoes and fungivores increases. The Maturity Indices (Maturity Index [MI], ∑ Maturity Index [∑MI], cp 2–5 Maturity Index [MI25], and Plant Parasitic Index [PPI]) are means of the weighted cp value of the community or a component of the community. Abundance of low cp value nematodes indicate a stressed and degraded soil food web, while abundance of high cp value nematodes indicates a mature and stable soil food web. A measure of nematode community diversity is best achieved through Simpson's Reciprocal Diversity Index (1/D) (Simpson, 1949). The index represents the weighted mean of proportional genera abundances. The index considers both genera abundance and the evenness of each genera's distribution within the population.The estimates of economic and crop production impacts of PPNs vary widely. Losses of 12% of annual production are often cited, dating back to a paper by Sasser and Freckman (1987). Losses associated with PPNs are likely underestimated due to misdiagnosis as abiotic stress or attributed to other pests. Traditional management options have included crop resistance, rotations that include nonhost plant species, and nematicides (Galal et al., 2014; Kretschmer et al., 1997; Smiley & Yan, 2010; Smiley et al., 2014). Crop and soil management strategies that diversify biological communities offer a simple option to suppress PPNs and improve soil biological nutrient cycling in a safe and economical way. These strategies reduce or eliminate the need for highly toxic and expensive nematicides (Held et al., 2003; Stark et al., 2000). Significant research efforts have focused on controlling PPNs using the traditional methods described above, while the impacts on free‐living soil nematode community is less well understood. Knowledge gaps in nematode ecology, specifically of farming systems in cool semi‐arid regions, still exist (Neher, 2010). A better understanding of how cropping systems (the type and sequence of crops cultivated and the management practices they are subjected to) affect nematode diversity in cool semi‐arid regions is needed.Core IdeasNematode community dynamics were assessed in barley‐dominated cropping systems.Herbivorous nematode (PPN) populations were positively correlated with barley yields.Moisture stress was a significant driver in nematode community dynamics.Research efforts advocate for diverse and high‐intensity rotations even though continuous cereal production and the use of an extended 14‐to‐18‐mo fallow period are still prevalent in dryland agriculture (Carr et al., 2021). Crop rotation has long been an important cultural practice in integrated pest management. Rotating crops can suppress pests, enhance soil quality (fertility, organic matter, and structure), and improve system economics by reducing fertilizer use and conserving energy (Badaruddin & Meyer, 1990; Biederbeck et al., 1996; Campbell et al., 1992; Coxworth et al., 1996; Green & Biederbeck, 1995; Wright, 1990; Yao et al., 2013; Zentner et al., 2001). Legumes are commonly used as a nitrogen (N) source through N2 fixation, and research from Montana indicates an improvement in soil quality and available soil N and carbon (C) under crop rotations that include a pulse crop (Engel et al., 2017; O'Dea & Miller, 2011). The increasing markets available to pulses (specifically field pea [Pisum sativum L.], lentil [Lens culinaris Medik], and chickpea [Cicer arietinum L.]) correlate with increased adoption of these crops throughout the northern Great Plains (NGP). For example, pulse production in Montana grew from more than 240,000 ha in 2013 to nearly 400,000 ha in 2019 (Montana Department of Agriculture, 2021). The economic value of incorporating pulses into rotations with cereals was demonstrated by Miller et al. (2015), whereby alternating pea with wheat (Triticum aestivum L.) increased net returns by US$287 ha−1 over 4 yr compared with wheat–fallow. Burgess et al. (2012) observed a 53% reduction in energy inputs in wheat‐based cropping systems when pulses were incorporated into the system.Even though this and other research have documented the benefits of incorporating annual legumes into wheat‐based systems (Long, Lawrence, Miller, & Marshall, 2014; Long, Lawrence, Miller, Marshall, & Greenwood, 2014; Luce et al., 2020; Smith et al., 2017), little is known about the impact of cropping system diversity on nematode community structure in the NGP and other cool semi‐arid regions. Research in other climates can provide clues of important impacts on nematodes in the NGP. For example, several studies indicate that conversion to no‐till and diversifying crop rotations can have positive impacts on the nematode community by increasing total numbers and diversity of genera present (Bakonyi et al., 2007; Eisenhauer et al., 2011; Ito, Araki, Higashi, et al., 2015; Ito, Araki, Komatsuzaki, et al., 2015; Pan et al., 2012). The finding that plant diversity in grasslands induced positive changes in nematode communities by increasing species diversity and richness, as well as stimulating and stabilizing nutrient cycling, is suggestive of the impact diversifying crop rotations could have on soil nematodes in dryland farming systems (Eisenhauer et al., 2011). Importantly, a 2015 study noted that tillage had a larger impact on the nematode community than either cover crop or fertility, with no‐till often having at least twice the abundance of nematodes than with moldboard plow (Ito, Araki, Higashi, et al., 2015). By limiting soil disturbance, farmers can foster soil ecosystem services (e.g., higher rates of soil nutrient cycling), in part because of a more diverse and resilient nematode community. This suggests that no‐till is a viable option to increase soil ecosystem services of nematodes, though these same positive impacts on the nematode community will also enhance survival and diversity of PPN populations.The current study determined the impact of four barley cropping systems on nematode community structure in semi‐arid central and southwestern Montana. Specifically, our objective was to compare the nematode community response in barley‐based systems that included and excluded field pea. We hypothesized that nematode community structure would be greatest in a barley–pea rotation and lowest in a barley–fallow system, with community diversity between those two extremes in a continuous barley monoculture.MATERIALS AND METHODSStudy site and experimental designThe study included a 3‐yr field experiment at the Montana State University (MSU) Arthur H. Post Farm (Post Farm) near Bozeman in southwestern Montana, and two, 3‐yr field experiments at the Central Agricultural Research Center (CARC) near Moccasin in central Montana. The Post Farm site (45°40′45“N, 111°8′45”W) is at an approximate elevation of 1,474 m on an Amsterdam‐Quagle silt loam soil (fine‐silty, mixed, superactive, frigid Typic Haplustoll) (Soil Survey Staff, 2017). Field history was 3 yr of chemical and tilled fallow prior to trial initiation. The seedbed was prepared using a cultivator equipped with S tines before sowing plots each spring during the experiment. Each fall after harvest, soil was plowed once using a 1.8‐m tandem disk. Precipitation at the Post Farm for 2017 and 2018 growing seasons (April through September, 272 mm and 297 mm, respectively) was similar to, or exceeded, the 30‐yr average (267 mm, Figure 1), though deficits were observed during July 2017 and 2018 when grain fill was occurring. Growing‐season precipitation totaled only 236 mm during 2016.1FIGUREMonthly weather data for Arthur H. Post Farm, Bozeman, MT, and the Central Agricultural Research Center, Moccasin, MT, for January 2015–September 2018The CARC site (47°3′30“ N, 109°56′57” W) is at an approximate elevation of 1,275 m on a shallow Danvers‐Judith clay loam soil (fine, smectitic, frigid Vertic Argiustoll) (Soil Survey Staff, 2017). Prior to trial initiation the plot area was previously winter wheat (Triticum aestivum L. emend. Thell.) and the field had been managed under no‐till for >5 yr. Precipitation at CARC was above the 30‐yr growing‐season average of 299 mm in 2016 and 2018 (330 and 329 mm, respectively, Figure 1). Growing season precipitation totaled only 261 mm during 2017, with a significant portion of it (∼65 mm) coming in September, after plots had been harvested. July and August precipitation in 2018 was also below average, possibly leading to reduced yield potential during grain fill.Plots at CARC were 4.6 by 6 m, while those at the MSU Post Farm were 3.7 by 6 m. Plots were seeded at the Post Farm using a 1.2 m wide small‐plot planter mounted with double disc openers, while at the CARC two different 1.5‐m wide small‐plot planters were used. A planter with hoe openers that removed crop residue in the furrow just before seed placement was used in one experiment while a planter with low‐disturbance, Acra Drill double‐disc openers (ShieldAg Equipment) mounted to the frame was used in the other experiment. No additional soil disturbance (i.e., tillage) occurred in the experiments at the CARC. The two CARC field experiments were situated approximately 25‐m apart in the same field.The three field experiments were established in 2016 at the Post Farm (tilled experiment) and the CARC (two no‐till experiments). The cropping systems included four, 2‐yr sequences: barley–pea for grain, barley–pea brown manure (i.e., pea crop terminated chemically at first flower (BBCH 60; Lancashire et al., 1991), barley–barley (i.e., continuous barley), and barley–fallow. Spring barley cultivar Hockett, an MSU malting cultivar well adapted to dryland conditions, was seeded at 200 seeds m−2 at both locations. A high‐yielding spring yellow pea cultivar Montech 4152 was seeded at a density of 80 seeds m−2. The treatments were arranged so that all phases of each cropping system (e.g., barley and pea) were present each year of the study. The phases were established in a randomized complete block design with four replicate blocks in each field experiment.Grass and broadleaf weeds and insect pests were controlled using labeled pesticides when necessary. The pea brown manure treatment was terminated with glyphosate and 2,4‐dichlorophenoxyacetic acid. Barley was managed so 30 kg N ha−1 Mg grain−1 was available at planting. Fertilizer was supplied for adequate soil nitrate‐N to meet barley yield goals (2 Mg ha−1 for Post Farm and 1 Mg ha−1 for CARC) based on soil test results and estimates of N mineralization from the previous year's leguminous residues where present (28 kg ha−1 if harvested for grain; 56 kg ha−1 if used as a manure; modified from McCauley et al., 2012), straw immobilization when the previous crop was barley (45 kg ha−1), and N mineralization from soil organic matter (SOM) over winter (assuming 2% SOM is recalcitrant but each percentage increment of SOM above 2% provides 22 kg ha−1) based on previous soil test results. Urea fertilizer was applied by subsurface banding just prior to sowing at CARC and by a surface broadcast application prior to sowing at the Post Farm.Sowing dates were as follows: the no‐till disc opener trial was seeded on 20 Apr. 2016, 11 May 2017, and 16 May 2018; the no‐till hoe opener trial was seeded on 21 Apr. 2016, 11 May 2017, and 15 May 2018; and the tilled disc opener trial was seeded on 21 Apr. 2016, 4 May 2017, and 4 May 2018. Additionally, two plots in the no‐till disc opener trial and one plot in the no‐till hoe opener trial were replanted on 13 June 2018 due to a sprayer error that year.Agronomic and soil dataThree 30‐cm deep by 3 cm in diameter soil cores were extracted per plot each spring prior to sowing crops or implementing fallow practices, and in 2018 following harvest. In addition, two soil cores of 30‐cm deep by 3 cm in diameter per plot were extracted per plot after crops had been harvested in 2016 and 2017. Sampling immediately prior to planting provided a snapshot of the nematode community present for plant colonization, while sampling after harvest indicated succession within the community after plant colonization. The first core during a sampling period was used to determine gravimetric and volumetric soil moisture to standardize nematode counts on a dry soil basis, while the second core was used for nematode extraction and faunal analysis. When taken, the third soil core was used for soil chemical analysis. Each soil core was put in a polypropylene‐lined tin‐tie soil bag (i.e., “coffee” bag) and placed inside a cooler immediately after sampling for transport. Samples were refrigerated at 4 °C until processing. All samples were processed within 4 wk of collection.Soil chemical analysis was performed by Agvise Laboratories in Northwood, ND, according to prescribed laboratory methods for soil nitrate (0–15 cm and 15–30 cm) and SOM (0–30 cm, Combs & Nathan, 2012; Gelderman & Beegle, 2012). Soil pH, phosphorus (P), potassium (K), and salt were also determined according to recommended methods (Frank et al., 2012; Peters et al., 2012; Warncke & Brown, 2012; Whitney, 2012)Grain from barley and pea in the middle 7.2 m2 at the Post Farm and 9 m2 at the CARC in each plot was collected using a small plot combine for yield. After harvest, grain was cleaned of detritus, weighed, and moisture determined using a Dickey‐John Grain Analysis Computer (GAC) 2500 (Dickey‐John Corporation). Yield was calculated using grain clean weights and reported on a 14% moisture basis.Soil nematode analysisSoil cores from the field were well mixed and soil extractions of approximately 25 g of fresh soil were performed using the Baermann funnel technique (Flegg & Hooper, 1970). Extractions ran for 72 h after which water suspension samples of at least 15 ml were collected. Nematodes were counted and the first 100 identified to genus level on a nematode counting slide (Chalex Corp.) using a Motic AE2000 inverted microscope with phase contrast (Motic North America). Nematode density was adjusted to total individuals per 100 g on a dry soil basis. Nematodes were assigned to a trophic group, a cp value, and a functional guild. Community structure was assessed using trophic group (feeding habit) and cp value (assigned a number from 1 to 5, 1 being a resource opportunist/early colonizer or 5 indicating a stabile food web) information followed by calculation of ecological indices following Ferris et al. (2001). Metabolic footprints were computed for components of the nematode community as described by Ferris (2010) and were facilitated using the Nematode INdicator Joint Analysis (NINJA) 2.0 (https://shiny.wur.nl/ninja/) R Shiny application developed by Sieriebriennikov et al. (2014). Simpson's Reciprocal Diversity Index (1/D) was calculated as follows: D = N(N – 1)/∑n(n – 1), where D = Simpson's Diversity Index, N = total number of individuals from all genera identified, and n = number of individuals from a specific genus. The inverse of D is then taken to scale the index to the number of genera identified.Statistical analysisData were subjected to ANOVA for a randomized block repeated measures design using the lmer function in the lme4 mixed‐effects model package in the R version 4.1.2 software environment (Bates et al., 2015), where cropping system was the whole plot with crop phase nested within cropping system and time (a combination of year and sample timing) as the subplot. Block was a random effect, and all other factors were considered fixed. Where the assumptions of normality and homoscedasticity were not met, original data were transformed using ln(x+1) prior to analysis. Back‐transformed data means are reported. Differences among treatment means were assessed using Tukey's HSD post‐hoc at an α < .05 unless otherwise stated. Where interaction of terms occurred, differences were assessed using the predictmeans package in R (Luo et al., 2018). Pearson's product‐moment correlations were obtained for total soil nitrate in the 30‐cm profile, total salt in the 30 cm, and crop (barley and pea) grain yield with nematode community structure (n = 48 at each trial location) using the cor.test function in base R. Correlations for total soil nitrate and total soil salt were only obtained for those sample timings where soil chemical analysis was performed, meaning data from prior to planting in all 3 yr and post‐harvest in 2018 were used. Correlations with yield data were obtained from all post‐harvest sample timings. Due to environmental variability (Figure 1), each field experiment was analyzed separately. Table 1 is the ANOVA table with p values for associated response variables.1TABLEAnalysis of variance table for main effects and interactions of the relevant response variablesTimeMaturity IndexEnrichment IndexStructure IndexGenera richnessInverse Simpson's Diversity IndexTotal nematodesTotal herbivoresHerbivore in total populationFree‐living populationFungivoreBacterivoreOmnivoreindividuals per 100 g dry soil%Tilled disc drill Post Farm p valueCS.92.91.92.41.85.52.73.82.95.95.93 p valueT.86<.01.35.02<.01<.01.03.38<.01<.01.48 p valueCS×T.65.98.98.45.9.81.92.82.99.99.97 p valueCS×CP.61.02.87.2.14.41.1.52.41.45.92 p valueCS×T×CP.23.991.94.99.56.94.73.94.991No‐till hoe drill CARC p valueCS.95.88.93.95.52.89.93.26.81.72.98 p valueT.2.45.01.35.54<.01.03.02.5.33.02 p valueCS×T.88.97.59.87.44.89.99.39.78.9.86 p valueCS×CP.83.36.95.22.46.25.62.1.24.54.94 p valueCS×T×CP.95.99.99.09.15.99.99.98.99.99.99No‐till disc drill CARC p valueCS.94.74.98.96.94.78.55.92.99.87.85 p valueT.01.02.2.09.01.05<.01.03.17.09<.01 p valueCS×T.92.25.89.73.94.73.35.43.94.99.94 p valueCS×CP.8.21.99.3.26.17.19.11.79.44.81 p valueCS×T×CP.99.99.99.99.99.99.99.93.99.99.89Note. CARC, Central Agricultural Research Center; CP, crop phase; CS, cropping system; Post Farm, Montana State University Arthur H. Post Farm; T, time.RESULTSAgronomic dataBarley grain yields were not different across cropping systems in any of the trials (p > .25, Table 2). Barley yield averaged 1.0 Mg ha−1 in both the hoe opener and disc opener no‐till field experiments at the CARC across the 3‐yr study, and 4.0 M ha−1 in the tilled field experiment at the Post Farm. Pea yield averaged < 0.7 Mg ha−1 in the no‐till field experiments and 2.3 Mg ha−1 in the tilled field experiment. The relatively low grain yields in the no‐till field experiments at the CARC are partially explained by below‐average precipitation received during grain fill (July–mid‐August; Figure 1), coupled with shallow soils limited ability to store water. Above‐average precipitation received each fall refilled stored water reserves of deep soils and helped explain the relatively high average yield in the tilled experiment at the Post Farm, which exceeded the yield goal by 2 Mg ha−1.2TABLECrop yields for each trial and year of the study. Yields did not significantly differ among trials or years within each cropping systemTrialYearBarleyPeaMg ha−1No‐till disc drill CARC20161.60.720170.70.420180.70.4No‐till hoe drill CARC20161.71.120170.70.420180.70.5Tilled disc drill Post Farm20164.62.520173.91.920183.42.6Note. CARC, Central Agricultural Research Center; Post Farm, Montana State University Arthur H. Post Farm.Correlations of nematode data with agronomic dataCropping system (e.g., barley–pea, barley–barley, barley–fallow) failed to affect nematode populations consistently in each of the three field experiments (data not presented, p > .15). However, crop yield (barley and pea) was correlated to the nematode population. Barley grain yield was moderately correlated with both the percentages of PPNs (r = .43) comprising the total nematode population, and fungivores in the free‐living communities (r = −.42), in the tilled experiment at the Post Farm (Table 3). This indicates an inverse relationship between PPNs and fungivores in regard to barley yield under tillage in a cool semi‐arid environment, where yield increases with an increasing percentage of PPNs comprising the community and decreases with higher percentages of fungivores.3TABLEPearson's product‐moment correlations for total soil nitrate, total soil salt, and grain yieldFree‐living populationCorrelation coefficient estimateTotal nematodesTotal herbivoresInverse Simpson's Diversity IndexHerbivore of total populationFungivoreBacterivoreOmnivoreEnrichment IndexStructure IndexMaturity IndexPlant Parasitic IndexTilled disc drill Post FarmTotal soil nitratea,b−.14−.11−.18.21*−.47**.38**−.19*.21*−.21*−.10−.35**Total soil salta−.31**−.27*−.38**.14−.49**.46**−.24*.16−.33**−.10−.52**Barley yield.04.26−.07.43**−.42**−.02−.09−.01−.08.04.07Pea yield−.33−.40−.25.12.26−.49−.39−.56−.21.51.46No‐till hoe drill CARCTotal soil nitratea−.06.12−.34**.41**−.31**−.21*−.13−.07−.06.02−.06Total soil salt−.21−.27*.27*−.22.11.06.22.12.17.16.03Barley yield.66**.62**−.42**.28.42**−.06−.51**−.43**−.38**−.38**−.49**Pea yield.47.08.21−.26.53.07−.63*.12−.58*−.58*−.05No‐till disc drill CARCTotal soil nitratea.22*.32**−.34**.33**−.08−.30**−.18.00−.29**−.23*−.07Total soil salt.02.04−.01.13−.02−.11−.07−.03.06.01−.12Barley yield.63**.68**−.20.38**−.04−.13−.42**.07−.43**−.43**.08Pea yield.52.35−.18−.20.78**.08−.48−.43−.60*−.53−.15Note. CARC, Central Agricultural Research Center; Post Farm, Montana State University Arthur H. Post Farm.aBack‐transformed from ln(x+1).bData for total soil nitrate and total soil salt correlations are from the pre‐plant sample timings in 2016–2018 and the post‐harvest sample timing in 2018. Data for yield correlations are from all post‐harvest sample timings.*Significant at the .05 probability level.**Significant at the .01 probability level.Barley grain yield in the no‐till field experiments at the CARC had strong associations to nematode community structure. In both trials, yield was positively correlated to total PPNs in the community (r ≥ .6, Table 3), indicating that yield increased with increasing PPN numbers under no‐till. There was also a strong correlation to total nematode population under no‐till.Some negative correlations to barley yield were observed under no‐till. The MI, SI, and the percentage of omnivores comprising the free‐living population were all negatively correlated to yield in both no‐till field experiments (r > −.38, −.38, and −.51, respectively, in the no‐till hoe drill and −.43, −.43, and −.4,2, respectively, in the no‐till disc drill, Table 3). Moisture stress during July and into August (Figure 1) coincided with an increase in omnivore composition of the free‐living nematode population under no‐till (Table 4). A greater relative number of omnivores would increase the average of both SI and MI. The negative correlation of these response variables to yield may be an echo of moisture stress impacting yield.4TABLEComposition and magnitude indicators of the nematode community. Data presented are averaged across cropping system and crop phaseTimeTotal nematodesTotal herbivoresHerbivore in total populationFree‐living populationaFungivoreBacterivoreOmnivoreindividuals per 100 g dry soil%Tilled disc drill Post Farm2016 pre327Bb136ABb3673A27C12016 post703A177A2934BC68AB12017 pre1,104A333A2543B57B12017 post1,060A336A2943B55B22018 pre702A186A2538BC59AB32018 post183B54B2927C73A1F ratio4.01**2.68*1.073.69**4.32**0.91No‐till hoe drill CARC2016 pre1,412Ab918Ab40BC39506C2016 post1,614A627A62A395612BC2017 pre479B79B30C383727A2017 post433B117B28C313121AB2018 pre465B178B51AB493020AB2018 post387B200B40BC452918ABF ratio3.65**2.60*2.84*0.871.162.80*No‐till disc drill CARC2016 pre1,134Ab559Ab62A365113C2016 post1,040A523A52AB444813C2017 pre1,095A414A47B413818BC2017 post462B170B40B324028AB2018 pre416B183B46B423922ABC2018 post386B142B44B413133AF ratio2.30†3.36**2.63*1.59 1.99†3.74**Note. CARC, Central Agricultural Research Center; Post Farm, Montana State University Arthur H. Post Farm. Letters indicate significant differences among timings by trial.aFree‐living population data does not include predatory nematodes. Total percentage may not equal 100.bBack‐transformed from ln(x+1).*Significant at p < .05.**Significant at p < .01.†Significant at p < .1.Pea grain yield had a smaller sample size of data for nematode correlations (n = 12 for each trial) than barley. Still, strong associations were observed under no‐till conditions, although there was a lack of consistency across the two field experiments. Pea grain yield was positively correlated to the percentage of fungivores comprising the free‐living population in one of the no‐till experiments (r = .78), while it was negatively correlated to the percentage of omnivores in the other (r = −.63; Table 3). No correlation was detected between pea grain yield and any nematode‐related trait in the tilled environment.Correlations of nematode data with soils dataSoil nitrate had only moderate relationships (|.30| < r < |.50|) with nematode parameters. Soil nitrate was correlated with genera diversity in both no‐till field experiments (r = −.34, Table 3), indicating that as soil nitrate increased, nematode diversity decreased. The percentage of PPNs comprising a population was positively correlated to nitrate (r > .33), indicating that as soil nitrate increases so, too, does the PPN population. A negative correlation between soil nitrate and bacterivore composition was detected (r < −.30). Conversely, in the tilled field experiment associations with soil nitrate were observed for the percentage of both bacterivores and fungivores in the nonherbivorous population (r = −.47 and .49). The relationship of bacterivores and fungivores with soil nitrate shows that as nitrate increases in the soil, fungivores decreased while bacterivores increased.Total salt content in the soil was associated to PPI and to fungivore and bacterivore populations in the tilled field experiment (Table 3). The PPI had a correlation coefficient of −.52 (Table 3), indicating a reduction of the PPN community's cp value under salt stress. Fungivores and bacterivores had an opposite relationship to soil salt, similar to soil nitrate content, where fungivores decreased (r = −.49) and bacterivores increased (r = .46). Nitrogen was applied in the form of urea at much higher rates at the Post Farm than at CARC because of differences in the anticipated barley yields. These higher application rates could explain the many negative associations observed for not only PPI, but total nematodes, total herbivorous nematodes, genera diversity, percentage of fungivores, percentage of omnivores, and SI. Each of these parameters represents a part of the community susceptible to salt disturbance in the soil environment. Weak associations were observed between salt content and total PPNs and genera diversity (r = −.27 and .27) in the no‐till hoe opener field experiments. As total salt increased in the soil, total PPNs decreased on average, while genera diversity increased.Description of nematode populations over the duration of the studyPost farm tilled disc opener trialThe nematode community shifted in the tilled seedbed at the Post Farm from a fungivore dominated community in 2016 to a bacterivore dominated community by 2018 (Table 4). Fungivores comprised 73% of the nonherbivorous community prior to planting during 2016, but only 27% by the final sampling in fall 2018. Conversely, bacterivores rose from 27 to 73% during the same time period. Total nematode population also fluctuated annually, with populations peaking at 1,104 individuals 100−1 g−1 dry soil prior to planting in 2017 and low populations both prior to planting in 2016 and following harvest in 2018 (327 and 183 individuals 100−1 g−1 dry soil, respectively). This population change was driven in large part by increases in the PPN population, peaking following harvest of 2017 at 336 individuals per 0.1 kg dry soil with populations crashing 12 mo later in the fall 2018 to 54 individuals 100−1 g−1 dry soil.CARC no‐till trial (hoe and disc)The nematode population decreased significantly over the duration of this experiment but not across cropping sequence. Total nematode population fell in both treatments (Table 4). Similarly, in the PPN community, there were 627 total PPNs 100−1 g−1 dry soil after harvest in 2016 compared with 200 total PPNs 100−1 g−1 in fall 2018.Compositional and ecological index changes were observed in the PPN and omnivore communities. The PPNs comprised 62% of the total population in fall 2016 and 51% in spring 2018 (Table 4). For all other sampling times, they never comprised >40% of the population. Interestingly, the SI increased from a low of 29 prior to planting in 2016 to a peak of 67 prior to planting in 2017 and plateauing in the following years (Table 5). This is corroborated by a significant increase in the percentage of omnivores from 6% of the community prior to planting in 2016 to a high of 27% prior planting in 2017 (Table 4).5TABLEEcological indicators of the nematode communityTimeMaturity IndexEnrichment IndexStructure IndexGenera RichnessInverse Simpson's Diversity IndexTilled disc drill Post Farm2016 pre1.9160A410B4.8B2016 post1.9839B39B4.9B2017 pre1.9056A1013A7.0A2017 post1.8957A914A6.2A2018 pre1.9651A1613A6.4A2018 post1.9336B68B4.5BF ratio0.384.15**1.122.82*3.86**No‐till hoe drill CARC2016 pre2.223129B125.32016 post2.283533B116.12017 pre2.574367A138.22017 post2.764161A147.92018 pre2.474352A137.52018 post2.564053A136.5F ratio1.480.953.05*1.120.82No‐till disc drill CARC2016 pre2.24C4137115.0C2016 post2.42BC4350125.5BC2017 pre2.51AB4860146.4ABC2017 post2.72A3968157.4AB2018 pre2.53AB4155137.8A2018 post2.76A4264136.7ABCF ratio3.15*2.78 1.49 1.973.09*Note. CARC, Central Agricultural Research Center; Post Farm, Montana State University Arthur H. Post Farm. Letters indicate significant differences among systems across all 3 yr by location and by year and timing.*Significant at p < .05.**Significant at p < .01.While total nematode populations generally declined irrespective of the crop sequence during the study, genera diversity increased at the same time, reaching a peak of 7.8 on Simpson's Reciprocal Diversity Index prior to planting in 2018 (Table 5), following much the same trend as the percentage of omnivores in the nonherbivorous community (Table 4). The MI similarly increased from a low of 2.24 in the spring 2016 to a high of 2.76 by the end of the study in the fall 2018 (Table 5), further corroborating the increased composition of the higher cp value omnivores in the community.DISCUSSIONResearch suggests that soil nematode communities can be indicators of soil health. However, few studies have assessed soil nematode community structure under grain crop systems in cool semi‐arid regions such as the NGP. We observed differences in nematode communities across time and crop yield, but not cropping system. The tilled field experiment was characterized by a shift in dominant decomposer channels, from fungivorous to bacterivorous nematodes. The no‐till field experiments were characterized mostly by reductions in abundance and changes in composition.Lack of cropping systems impact on the nematode populationTwo factors impacted our ability to observe differences in this study: (a) the short duration of the study (3 yr) and (b) the limited sampling resolution in terms of soil sample density and timings. Dryland systems in northern semi‐arid climates take longer to show differences to management strategies due in part to the biological processes in the soil being considerably slower than in wetter, warmer environments. A meta‐analysis by Pittelkow et al. (2015) indicated that when transitioning to no‐till in dry climates, yields only begin to recover after 3–4 yr with yields similar to conventional tillage happening on average after 5 yr.Second, the resolution in nematode sampling was relatively limited. Our study only captures a snapshot of the nematode community at planting in the spring with ample moisture from winter snows and immediately following harvest in late summer, typically after the soils have dried significantly. Adding at least a mid‐season sampling time would have increased our temporal sample resolution over the course of the study. Additionally, we were limited on spatial density due to small plot size. Had plot size been larger, higher density sampling would have been more conducive. We chose one core per plot as we wanted to avoid mining away the soil as the trials progressed.Most studies looking at nematode communities and crop yield have focused on control of herbivorous nematodes, but few have seen positive correlations between yield and herbivorous nematodes. Burkhardt et al. (2019) determined that a perennial legacy in dryland wheat‐based systems led to higher cp value nematodes, including PPNs. Zhang et al., 2017 determined that biofertilizers (derived from manure compost and inoculated with certain bacterial strains) in sugarcane (Saccharum officinarum L.) production significantly increased the abundance of free‐living nematodes while decreasing the abundance of PPNs. Other studies determined the impact of cover crops on community structure, indicating increased nematode community structure and crop yield in cropping systems using cover crops (Leslie et al., 2017; Wang et al., 2011). The short time frame of the current study limited the observable changes due to cropping system, especially when overwhelmed by factors such as moisture, overwinter stresses, tillage, and other factors in the short term.We did not observe a negative impact on yield in the rotations without fallow, which could occur due to less soil moisture, perhaps because pea plants have a shallower root system than barley and use moisture from different soil depths. Also, barley yield across all systems was statistically similar within each location even though fertilizer rates differed across crop sequences for the same yield goal. Fertilizer rates were based on soil test results and estimates of residue mineralization rates as suggested by Miller et al. (2015), resulting in less urea fertilizer applied to barley following pea than following barley or fallow. Therefore, growers could benefit from barley pulse rotations, utilizing less fertilizer and having more ground cover while allowing for a crop to be harvested each season without detrimental impacts to yield.Agronomic correlationsCorrelations to barley yield at the Post Farm may point towards a more balanced community. A community comprised largely of fungivores is likely to have a lower average cp value of the whole community (i.e., lower MI). Significant correlations likely were not observed for the other community components due to the dominance of PPNs and bacterivores in the nematode community under tillage. The strong positive correlations at the CARC could indicate that the nematode population is enhanced under favorable plant growth conditions, as several metabolic footprints were also positively correlated to higher yield.Correlations between nematode community structure and soil nitrate, soil salt, and crop yield revealed much about the study and the field experiments. The no‐till experiments, performed at CARC in shallow soils were dominated by moisture and water stresses during critical grain‐fill stages, with cascading effects on the nematode community. Soils at the CARC are notoriously shallow, with some areas on the site being only 30–60 cm before reaching parent material. Increased SI was significantly correlated to lower crop yields in both no‐till experiments, as was MI in one of the experiments. The decrease in yield is likely a coincidence with moisture and other stresses and not caused by increased nematode community structure or maturity indices.More interesting might be the correlations between the nematode community and soil characteristics. We only conducted correlations with total soil salt. Bacterivores and fungivores had inverse correlations to soil salt and nitrate in the tilled experiment, suggesting bacterivores are more tolerant to higher salt and nitrate in the soil than fungivores. All indices and measures with significant correlations to soil salt were negatively correlated, except for bacterivores. This corroborates evidence from experiments in Germany and Vietnam suggesting salinity tolerance of some bacterivorous nematode families (Nguyen et al., 2021; Schmidt et al., 2020). Similarly, correlations were negative when detected between soil nitrate and nematode indices and measures, with the exception of percentages of PPNs and bacterivores comprising the nematode population, and EI. Bacterivores comprise a portion of the genera needed for calculating EI, so the positive association with soil nitrate is apparent. Although the percentage of PPNs comprising a population was correlated with soil nitrate, the correlation between soil nitrate and PPI was negative. The positive association of PPNs and negative association of PPI suggests that only low cp value nematodes are tolerant to higher soil nitrate levels. The PPNs with low cp values are typically algal, lichen, and moss feeders and not of economic importance (Bongers et al., 1995), explaining why an increase in PPNs did not impact yield.Trends in the field experimentsThe trend in increased nematode populations at the Post Farm coincides with most plots being “re‐cropped” (fallow plots being the exception) and subsequently recolonized by herbivorous and bacterivorous nematodes after several years of fallow. The community shift in the tilled experiment from fungivores to bacterivores may be linked to field history and management prior to establishment. The field was fallow during the 3 yr prior to initiating the study, except for a single tillage operation each fall, likely defining the nematode community prior to the establishment of the field experiment. We suspect that the more frequent tillage operations coupled with more plant organic matter during the field experiment fundamentally shifted the nematode community from a fungivore dominated nematode community to one dominated by low cp value bacterivorous nematodes. Our results confirm previous studies, where tillage had a greater influence on community structure by creating an environment more favorable to bacterivores than fungivores than cultural practices like cropping system (Ito, Araki, Higashi, et al., 2015). We speculate the decreasing trends in population during the fall of 2018 may be due to soil moisture deficits in mid‐summer driving nematode populations deeper in the soil profile.Prior field management was more stable for the no‐till field experiments, where no‐till, continuous cropping had been in place for several years prior to establishment of the two no‐till experiments. Cropping system differences were not detected in either experiment, possibly because 3 yr (length of the study) was too short for significant changes in the relatively stable and resilient nematode community already in place (Raffaelli & White, 2013). The high cp value nematodes, omnivores specifically, were more persistent than lower cp, basal fungivores, and bacterivores over the duration of the study (Table 4), perhaps reflecting omnivores greater resilience to soil‐moisture stress, resulting from low precipitation (Figure 1). Increased abundance of omnivores in turn increased MI, SI, and omnivore composition of the community, which are often indicators of a more balanced community (Bongers, 1990; Ferris et al., 2001).Previous research supports speculation that omnivorous nematodes are more resilient to moisture stress than fungivores and bacterivores. Landesman et al. (2011) found that the family Qudsianematidae, which includes the omnivore genera detected in the present study, along with the family Cephalobidae, were the least sensitive to low soil moisture stress in a precipitation exclusion experiment. Yan et al. (2018) noted that some genera of PPNs were less susceptible to drought than others, some of which overlap with genera observed in the no‐till experiments. A more structured nematode community evolved in a study on semi‐arid shrub land as soil dried and warmed, from an average SI of 66 in the control, to 74 in a dried soil treatment and 73 in the warmed soil treatment (Bakonyi et al., 2007). A similar increase in SI was detected in the no‐till hoe opener experiment in our study (Table 5).Correlations between soil nitrate, increased PPNs, and decreased community diversity in no‐till trials indicate negative impacts of increasing soil N on the nematode community. These correlations could be exacerbated by water stress, leading to higher osmotic stress where pockets of nitrate occur.CONCLUSIONSThis study provides a first description of nematode communities under two tillage systems and four different cropping systems in the semi‐arid climate in the NGP. Cropping systems studies in cool semi‐arid regions can often take several years before differences in soil properties are detected. The present study details changes over a 3‐yr period under dryland grain‐based systems. Pearson's correlation coefficients suggest that there where the environment is conducive for higher barley yield, it is also a better environment for nematodes. The main limiting factor in Montana dryland production is water and as nematodes are susceptible to dry conditions, when water is sufficient for barley growth so too is it sufficient for nematode populations to survive. While plant‐water stress had significant negative impacts on the nematode community in one of the no‐till experiments, SI was improved through the survival of more cp 4 omnivores. The differential response to environmental stresses of certain components of the nematode community would seem to be an important, if little studied, subject area. This study further supports the inclusion of field pea into Montana dryland rotations by showing that no negative effects were observed, even under significant moisture stress. Yield was maintained at similar levels to both barley–fallow and continuous barley cropping systems while also using less urea fertilizer.ACKNOWLEDGMENTSThis work was supported by the Montana Wheat and Barley Committee. Special thanks to Traci Hoogland, Megan Getz, Dylan Mangel, Joe Jensen, Sally Dahlhausen, Simon Fordyce, and Sherry Bishop for their assistance in the field at critical times.AUTHOR CONTRIBUTIONSAndy Burkhardt: Conceptualization; Data curation; Formal analysis; Investigation; Methodology; Project administration; Software; Validation; Visualization; Writing – original draft. Shabeg Briar: Resources; Supervision; Validation; Writing – review & editing. John M Martin: Formal analysis; Methodology; Software; Supervision; Validation; Visualization; Writing – review & editing. Patrick M Carr: Conceptualization; Methodology; Resources; Writing – review & editing. Jamie Sherman: Funding acquisition; Resources; Supervision; Validation; Writing – review & editing.CONFLICT OF INTERESTThe authors declare no conflict of interest.REFERENCESBadaruddin, M., & Meyer, D. W. (1990). Green‐manure legume effects on soil nitrogen, grain yield, and nitrogen nutrition of wheat. Crop Science, 30, 819–825. https://doi.org/10.2135/cropsci1990.0011183X003000040011xBakonyi, G., Nagy, P., Kovács‐Láng, E., Kovács, E., Barabás, S., Répási, V., & Seres, A. (2007). Soil nematode community structure as affected by temperature and moisture in a temperate semiarid shrubland. Applied Soil Ecology, 37, 31–40. https://doi.org/10.1016/j.apsoil.2007.03.008Bates, D., Mächler, M., Bolker, B., & Walker, S. (2015). Fitting linear mixed‐effects models using lme4. Journal of Statistical Software, 67, 1–48. https://doi.org/10.18637/jss.v067.i01Biederbeck, V. O., Rice, W. A., Kessel, C. v., Bailey, L. D., & Huffman, E. C. (1996). Present and potential future nitrogen gains from legumes in major soil zones of the Prairies, Saskatchewan Soils and Crops '96. University of Saskatchewan. https://harvest.usask.ca/handle/10388/10336Bongers, T. (1990). The maturity index: An ecological measure of environmental disturbance based on nematode species composition. Oecologia, 83, 14–19. https://doi.org/10.1007/BF00324627Bongers, T., & Bongers, M. (1998). Functional diversity of nematodes. Applied Soil Ecology, 10, 239–251. https://doi.org/10.1016/S0929‐1393(98)00123‐1Bongers, T., Goede, R. G. N. d., Korthals, G. W., & Yeates, G. W. (1995). Proposed changes of c‐p classification for nematodes. Russian Journal of Nematology, 3, 61–62.Burgess, M. H., Miller, P. R., & Jones, C. A. (2012). Pulse crops improve energy intensity and productivity of cereal production in Montana, USA. Journal of Sustainable Agriculture, 36(6), 699–718. https://doi.org/10.1080/10440046.2012.672380Burkhardt, A., Briar, S. S., Martin, J. M., Carr, P. M., Lachowiec, J., Zabinski, C., Roberts, D. W., Miller, P., & Sherman, J. (2019). Perennial crop legacy effects on nematode community structure in semi‐arid wheat systems. Applied Soil Ecology, 136, 93–100. https://doi.org/10.1016/j.apsoil.2018.12.020Campbell, C. A., Zentner, R. P., Selles, F., Biederbeck, V. O., & Leyshon, A. J. (1992). Comparative effects of grain lentil–wheat and monoculture wheat on crop production, N economy and N fertility in a Brown Chernozem. Canadian Journal of Plant Science, 72, 1091–1107. https://doi.org/10.4141/cjps92‐135Carr, P. M., Bell, J. M., Boss, D. L., Delaune, P., Eberly, J. O., Edwards, L., Fryer, H., Graham, C., Holman, J., Islam, M. A., Liebig, M., Miller, P. R., Obour, A., & Xue, Q. (2021). Using annual forages to enhance dryland wheat farming in the Great Plains. Agronomy Journal, 113, 1–25. https://doi.org/10.1002/agj2.20513Combs, S. M., & Nathan, M. V. (2012). Soil organic matter. In Brown, J. R. (Ed.). Recommended chemical soil test procedures for the North Central Region (pp. 53–58). Missouri Agricultural Experiment Station.Coxworth, E., Biederbeck, V. O., Campbell, C. A., Entz, M. H., & Zentner, R. P. (1996). A bioenergy success story: The energy savings implications of the increase in legumes in rotations since 1990, Saskatchewan soils and crops '96. University of Saskatchewan. https://harvest.usask.ca/handle/10388/10298Eisenhauer, N., Migunova, V. D., Ackermann, M., Ruess, L., & Scheu, S. (2011). Changes in plant species richness induce functional shifts in soil nematode communities in experimental grassland. PLOS ONE, 6, e24087. https://doi.org/10.1371/journal.pone.0024087Engel, R. E., Miller, P. R., Mcconkey, B. G., & Wallander, R. (2017). Soil organic carbon changes to increasing cropping intensity and no‐till in a semiarid climate. Soil Science Society of America Journal, 81, 404–413. https://doi.org/10.2136/sssaj2016.06.0194Ferris, H. (2010). Form and function: Metabolic footprints of nematodes in the soil food web. European Journal of Soil Biology, 46(2), 97–104. https://doi.org/10.1016/j.ejsobi.2010.01.003Ferris, H., & Bongers, T. (2006). Nematode indicators of organic enrichment. Journal of Nematology, 38, 3–12.Ferris, H., Bongers, T., & De Goede, R. G. M. (2001). A framework for soil food web diagnostics: Extension of the nematode faunal analysis concept. Applied Soil Ecology, 18, 13–29. https://doi.org/10.1016/S0929‐1393(01)00152‐4Ferris, H., & Matute, M. M. (2003). Structural and functional succession in the nematode fauna of a soil food web. Applied Soil Ecology, 23, 93–110. https://doi.org/10.1016/S0929‐1393(03)00044‐1Flegg, J. I. M., & Hooper, D. J. (1970). Extraction of free‐living stages from soil. Technical Bulletin. Ministry of Agriculture, Fisheries and Food, 5, 5–22.Frank, K., Beegle, D., & Denning, J. M. (2012). Phosphorus. In Brown, J. R. (Ed.). Recommended chemical soil test procedures for the North Central Region (pp. 27–35. Missouri Agricultural Experiment Station.Galal, A., Sharma, S., Abou‐Elwafa, S. F., Sharma, S., Kopisch‐Obuch, F., Laubach, E., Perovic, D., Ordon, F., & Jung, C. (2014). Comparative QTL analysis of root lesion nematode resistance in barley. Theoretical and Applied Genetics, 127, 1399–1407. https://doi.org/10.1007/s00122‐014‐2307‐xGelderman, R. H., & Beegle, D. (2012). Chapter 5 Nitrate‐nitrogen. In Brown, J. R. (Ed.). Recommended chemical soil test procedures for the North Central Region (pp. 23–26). Missouri Agricultural Experiment Station.Green, B. J., & Biederbeck, V. O. (1995). Farm Facts: Soil improvement with legumes, including legumes in crop rotations (Canada‐Saskatchewan Agreement on Soil Conservation Bulletin). Saskatchewan Agriculture and Food.Held, L. J., Opp, T. J., Koch, D. W., Gray, F. A., & Flake, J. W. (2003). Profitability of variable versus uniform rate nematicide for sugar beets. Journal of American Society of Farm Managers and Rural Appraisers, 2003, 74–83.Ito, T., Araki, M., Higashi, T., Komatsuzaki, M., Kaneko, N., & Ohta, H. (2015). Responses of soil nematode community structure to soil carbon changes due to different tillage and cover crop management practices over a nine‐year period in Kanto, Japan. Applied Soil Ecology, 89, 50–58. https://doi.org/10.1016/j.apsoil.2014.12.010Ito, T., Araki, M., Komatsuzaki, M., Kaneko, N., & Ohta, H. (2015). Soil nematode community structure affected by tillage systems and cover crop managements in organic soybean production. Applied Soil Ecology, 86, 137–147. https://doi.org/10.1016/j.apsoil.2014.10.003Kretschmer, J. M., Chalmers, K. J., Manning, S., Karakousis, A., Barr, A. R., Islam, A. K. M. R., Logue, S. J., Choe, Y. W., Barker, S. J., Lance, R. C. M., & Langridge, P. (1997). RFLP mapping of the Ha2 cereal cyst nematode resistance gene in barley. Theoretical and Applied Genetics, 94, 1060–1064. https://doi.org/10.1007/s001220050515Lancashire, P. D., Bleiholder, H., Boom, T. V. D., Langelüddeke, P., Stauss, R., Weber, E., & Witzenberger, A. (1991). A uniform decimal code for growth stages of crops and weeds. Annals of Applied Biology, 119(3), 561–601. https://doi.org/10.1111/j.1744‐7348.1991.tb04895.xLandesman, W. J., Treonis, A. M., & Dighton, J. (2011). Effects of a one‐year rainfall manipulation on soil nematode abundances and community composition. Pedobiologia, 54(2), 87–91. https://doi.org/10.1016/j.pedobi.2010.10.002Leslie, A. W., Wang, K. ‐. H., Meyer, S. L. F., Marahatta, S., & Hooks, C. R. R. (2017). Influence of cover crops on arthropods, free‐living nematodes, and yield in a succeeding no‐till soybean crop. Applied Soil Ecology, 117–118, 21–31. https://doi.org/10.1016/j.apsoil.2017.04.003Long, J. A., Lawrence, R. L., Miller, P. R., & Marshall, L. A. (2014). Changes in field‐level cropping sequences: Indicators of shifting agricultural practices. Agriculture, Ecosystems & Environment, 189, 11–20. https://doi.org/10.1016/j.agee.2014.03.015Long, J. A., Lawrence, R. L., Miller, P. R., Marshall, L. A., & Greenwood, M. C. (2014). Adoption of cropping sequences in northeast Montana: A spatio‐temporal analysis. Agric., Ecosystems & Environment, 197, 77–87. https://doi.org/10.1016/j.agee.2014.07.022Luo, D., Ganesh, S., & Koolaard, J. (2018). predictmeans: Calculate predicted means for linear models (R package version 1.0.6). https://mirrors.vcea.wsu.edu/r‐cran/web/packages/predictmeans/predictmeans.pdfMcCauley, A. M., Jones, C. A., Miller, P. R., Burgess, M. H., & Zabinski, C. A. (2012). Nitrogen fixation by pea and lentil green manures in a semi‐arid agroecoregion: Effect of planting and termination timing. Nutrient Cycling Agroecosystems, 92(3), 305–314. https://doi.org/10.1007/s10705‐012‐9491‐3Miller, P. R., Bekkerman, A., Jones, C. A., Burgess, M. H., Holmes, J. A., & Engel, R. E. (2015). Pea in rotation with wheat reduced uncertainty of economic returns in Southwest Montana. Agronomy Journal, 107, 541–550. https://doi.org/10.2134/agronj14.0185Montana Department of Agriculture. (2021). Pulse marketing and product information. Montana Department of Agriculture. https://agr.mt.gov/PulseMarketing#:~:text=Grow%20Montana%20Pulses&text=Statistics%20show%20that%20the%20total,who%20are%20exporting%20pulse%20cropsNeher, D. A. (2001). Role of nematodes in soil health and their use as indicators. Journal of Nematology, 33, 161–168.Neher, D. A. (2010). Ecology of plant and free‐living nematodes in natural and agricultural soil. Annual Review of Phytopathology, 48, 371–394. https://doi.org/10.1146/annurev‐phyto‐073009‐114439Nguyen, V. S., Chau, M. K., Vo, Q. M., Le, V. K., Nguyen, T. K. P., Araki, M., Perry, R. N., Tran, A. D., Dang, D. M., Tran, B. a. L., Chol, G. L., & Toyota, K. (2021). Impacts of saltwater intrusion on soil nematodes community in alluvial and acid sulfate soils in paddy rice fields in the Vietnamese Mekong Delta. Ecological Indicators, 122, 107284. https://doi.org/10.1016/j.ecolind.2020.107284O'Dea, J. K., & Miller, P. R. (2011). Greening summer fallow: Agronomic and edaphic implications of legumes in dryland wheat agroecosystems. Department of Land Resources and Environmental Sciences, Montana State University.Pan, F. J., Xu, Y.‐L. i., McLaughlin, N. B., Xue, A. G., Yu, Q., Han, X.‐Z., Liu, W., Zhan, L. i.‐L. i., Zhao, D., & Li, C.‐J. (2012). Response of soil nematode community structure and diversity to long‐term land use in the black soil region of China. Ecological Research, 27(4), 701–714. https://doi.org/10.1007/s11284‐012‐0944‐6Peters, J., Nathan, M., & Laboski, C. (2012). pH and lime requirement. In Brown, J. R. (Ed.). Recommended chemical soil test procedures for the North Central Region (pp. 16–22). Missouri Agricultural Experiment Station.Pittelkow, C. M., Linquist, B. A., Lundy, M. E., Liang, X., Van Groenigen, K. J., Lee, J., Van Gestel, N., Six, J., Venterea, R. T., & Van Kessel, C. (2015). When does no‐till yield more? A global meta‐analysis. Field Crops Research, 183, 156–168. https://doi.org/10.1016/j.fcr.2015.07.020Raffaeli, D., & White, P. C. L. (2013). Ecosystems and their services in a changing world: An ecological perspective. In Woodward, G., & O'Gorman, E. J. (Eds.). Advances in ecological research (pp. 1–70). Academic Press.Ritz, K., & Trudgill, D. L. (1999). Utility of nematode community analysis as an integrated measure of the functional state of soils: Perspectives and challenges. Plant and Soil, 212, 1–11. https://doi.org/10.1023/A:1004673027625Sasser, J. N., & Freckman, D. W. (1987). A world prospective on nematology: The role of the society. In Veech, J. A., & Dickson, D. W. (Eds.). Vistas on nematology (pp. 7–14). Society of Nematologists.Schmidt, J. H., Hallmann, J., & Finckh, M. R. (2020). Bacterivorous nematodes correlate with soil fertility and improved crop production in an organic minimum tillage system. Sustainability, 12, 6730, https://doi.org/10.3390/su12176730Sieriebriennikov, B., Ferris, H., & De Goede, R. G. M. (2014). NINJA: An automated calculation system for nematode‐based biological monitoring. European Journal of Soil Biology, 61, 90–93. https://doi.org/10.1016/j.ejsobi.2014.02.004Simpson, E. H. (1949). Measurement of diversity. Nature, 163, 688. https://doi.org/10.1038/163688a0Smiley, R. W., & Yan, G. (2010). Cereal cyst nematodes: Biology and management in Pacific Northwest wheat, barley, and oat crops (Pacific Northwest Extension Publication). Oregon State University.Smiley, R. W., Yan, G., & Gourlie, J. A. (2014). Selected Pacific Northwest crops as hosts of Pratylenchus neglectus and P. thornei. Plant Disease, 98, 1341–1348. https://doi.org/10.1094/PDIS‐12‐13‐1296‐RESmith, E. G., Zentner, R. P., Campbell, C. A., Lemke, R., & Brandt, K. (2017). Long‐term crop rotation effects on production, grain quality, profitability, and risk in the northern Great Plains. Agronomy Journal, 109(3), 957–967. https://doi.org/10.2134/agronj2016.07.0420Soil Survey Staff. (2017). Web soil survey. Natural Resources Conservation Service, U.S. Department of Agriculture. https://websoilsurvey.sc.egov.usda.gov/Stark, C. R. Jr., Dowler, C. C., Johnson, A. W., & Baker, S. H. (2000). A gross margin comparison of returns to nematicide treatment in continuous and rotation triticale‐soybean production. Journal of Agribusiness, 18, 319–329.St Luce, M., Lemke, R., Gan, Y., Mcconkey, B., May, W., Campbell, C., Zentner, R., Wang, H., Kroebel, R., Fernandez, M., & Brandt, K. (2020). Diversifying cropping systems enhances productivity, stability, and nitrogen use efficiency. Agronomy Journal, 112(3), 1517–1536. https://doi.org/10.1002/agj2.20162Wang, K.‐H., Hooks, C. R. R., & Marahatta, S. P. (2011). Can using a strip‐tilled cover cropping system followed by surface mulch practice enhance organisms higher up in the soil food web hierarchy? Applied Soil Ecology, 49, 107–117. https://doi.org/10.1016/j.apsoil.2011.06.008Warncke, D., & Brown, J. R. (2012). Potassium and other basic cations. In Brown, J. R. (Ed.). Recommended chemical soil test procedures for the North Central Region (pp. 36–38). Missouri Agricultural Experiment Station.Whitney, D. A. (2012). Soil salinity. In Brown, J. R. (Ed.), Recommended chemical soil test procedures for the North Central Region (pp. 63–64). Missouri Agricultural Experiment Station.Wright, A. T. (1990). Yield effect of pulses on subsequent cereal crops in the northern Prairies. Canadian Journal of Plant Science, 70, 1023–1032. https://doi.org/10.4141/cjps90‐125Yan, D., Yan, D., Song, X., Yu, Z., Peng, D., Ting, X., & Weng, B. (2018). Community structure of soil nematodes under different drought conditions. Geoderma, 325, 110–116. https://doi.org/10.1016/j.geoderma.2018.03.028Yao, R.‐J., Yang, J.‐S., Zhang, T.‐J., Gao, P., Yu, S.‐P., & Wang, X.‐P. (2013). Short‐term effect of cultivation and crop rotation systems on soil quality indicators in a coastal newly reclaimed farming area. Journal of Soils and Sediments, 13, 1335–1350. https://doi.org/10.1007/s11368‐013‐0739‐6Yeates, G. W., Bongers, T., De Goede, R. G. M., Freckman, D. W., & Georgieva, S. S. (1993). Feeding habits in soil nematode families and genera—An outline for soil ecologists. Journal of Nematology, 25, 315–331.Zentner, R. P., Campbell, C. A., Biederbeck, V. O., Miller, P. R., Selles, F., & Fernandez, M. R. (2001). In search of a sustainable cropping system for the semiarid Canadian Prairies. Journal of Sustainable Agriculture, 18(2‐3), 117–136. https://doi.org/10.1300/J064v18n02_10Zhang, F., Gao, C., Wang, J., Lu, Y., Shen, Z., Liu, T., Chen, D., Ran, W., & Shen, Q. (2017). Coupling sugarcane yield to soil nematodes: Implications from different fertilization regimes and growth stages. Agriculture, Ecosystem & Environment, 247, 157–165. https://doi.org/10.1016/j.agee.2017.06.020
Journal
"Agrosystems, Geosciences & Environment" – Wiley
Published: Jan 1, 2022