Pea Rotation Research Articles

Pea growth, yield, and quality affected by nitrogen fertilization to previous crop in small grain–pea rotations

AbstractStarter N fertilization at low rates may enhance pea (Pisum sativum L.) performance, but little information exists about the effect of N fertilization rate to previous crop (NRPC) on pea growth, yield, and quality in small grain–pea rotations. We examined the effect of N fertilization rates to barley (Hordeum vulgare L.) and spring wheat (Triticum aestivum L.) on succeeding pea growth, yield, and quality in barley–pea and spring wheat–pea rotations from 2006 to 2019 in the semiarid environment of US northern Great Plains. We measured pea plant density, straw and grain yields, harvest index, straw N concentration, grain protein concentration, grain test weight, straw and grain N uptake, and N harvest index. In the barley–pea rotation, pea grain yield increased with increased NRPC. Grain test weight was greater without than with NRPC in 2008 and 2009. In the spring wheat–pea rotation, straw yield was greater for 50 than 0 kg N ha−1 of NRPC in 2014, 2018, and 2019. Grain yield and N uptake were greater with than without NRPC in 2014, 2015, and 2019, but grain test weight varied with NRPC and year. Plant density, harvest index, straw N concentration, grain protein concentration, straw N uptake, and N harvest index varied with year in both barley–pea and spring wheat–pea rotations. Nitrogen fertilization to barley or spring wheat can enhance succeeding pea grain yield and N uptake during years with normal growing season precipitation in barley–pea and spring–wheat pea rotations in the semiarid region of the US northern Great Plains.

Phosphorus Availability and Uptake following a Maize-Pigeon Pea Rotation under Conservation Agriculture

Soils on many smallholder farms in Southern Africa are severely depleted in plant nutrients, in particular phosphorus (P), following years of maize monocropping with little or no fertilizer input. Past studies suggest that pigeon pea (Cajanus cajan (L.) Millsp.) may increase plant-available P. Pigeon pea is not a common crop in much of Southern Africa, and the effect of locally grown pigeon pea varieties on plant-available P is unknown. We assessed the changes in plant-available P after growing pigeon pea varieties MPPV-2, MPPV-3, and Babati White in Zambia, viz. Lixisols of Choma and Mkushi, Acrisols of Chipata and Kasama, and Arenosols of Kaoma. The selected soils were not fertilized. Baseline soils (0–20 cm), sampled after long-term maize monocropping and soils from the same fields after growing pigeon pea were collected from field trials in Kaoma, Chipata, Choma, and Mkushi and analyzed for plant-available P. Further, a greenhouse study was conducted with soils from Kasama, Choma, Kaoma, and Chipata, under which soil P was determined before and after growing pigeon pea, soybean (Dina), and maize (SC 419) without fertilizer addition. Pigeon pea under field studies had no significant (p > 0.05) effect on plant-available P in Choma, Kaoma, and Chipata. In Mkushi, pigeon pea cropping resulted in a 47.5% significant decline (p ≤ 0.05) in plant-available P, amounting to a loss of 11.2 kg ha−1. The greenhouse study showed a significant decline (p ≤ 0.001) in plant-available P after seven weeks of maize growth, while there was no significant (p > 0.05) effect on plant-available P after soybean and pigeon pea cropping. The latter was primarily due to the significantly higher P uptake associated with larger biomass production of maize after seven weeks in the greenhouse. During the initial seven weeks, pigeon pea biomass had significantly higher P concentrations than maize. Thus, P deficiency symptoms were exhibited in maize, while pigeon pea appeared healthy. However, mobilized P, calculated as the sum of plant P and soil P after cropping minus soil P before planting, was significantly lower (p ≤ 0.01) in pigeon pea compared to soybean and maize. Synthesizing field and greenhouse experiments suggests that there is a low net decline of plant-available P from soils after pigeon pea cropping. Therefore, rotation with these pigeon pea varieties could be beneficial to resource-poor farmers due to low P removal and its ability to grow in P-deficient soil.

Cropping System Stability Drives SOC Sequestration and Increases Saturation Deficit in Hot Arid Durum Wheat Cropping Systems

Stability analysis has been extensively employed in evaluating the genotype x environment interaction, but it can also be conveniently applied to cropping systems. This study applied stability analysis to a long-term experiment (1998–2016) conducted in an experimental farm in southern Italy. The experiment involved two standard semi-arid cropping systems (WW—durum wheat monocropping and WP—durum wheat–field pea rotation), with two nitrogen fertilization levels (60 kg ha−1—N60 and 120 kg ha−1—N120), along with an unfertilized control (N0). Soil organic carbon (SOC) was estimated in all treatments at the end of the experiment to investigate the potential for SOC sequestration and soil C saturation by analyzing the stability of all investigated cropping conditions in relation to SOC sequestration. The study also investigated the relationship between C input and SOC sequestration. SOC sequestration per year was higher in WW than in WP, confirming that including legumes in the rotation did not enhance the SOC content. Similarly, the positive impact of nitrogen application on biomass yield did not affect SOC accumulation. The stability analysis revealed that over the long term, WW exhibited greater stability than WP, suggesting that, in semi-arid environments, a more stable cropping system can enhance soil carbon sequestration, with nitrogen fertilization exerting a scarce influence. Segmented regression analysis identified two distinct patterns of SOC accumulation based on C input, separated by a definite threshold of C input (breakpoint) quantified at 14.7 Mg ha−1. It was found that the steady-state C level, achieved after the accumulation of this C input, was reached much faster in WW than in WP, in which it could only be inferred at 23 years. In conclusion, this study underscores the role of cropping system stability in driving SOC sequestration. Furthermore, it emphasizes the potential of stability analysis in assisting stakeholders in refining their strategies for different cropping conditions in dry and rainy environments.

Effects of Annual Crop Rotation and Fallow on Soil AMF Community and Aggregate Stability

To investigate the effects of crop rotation and fallow on the community composition of arbuscular mycorrhizal fungi (AMF) and the stability of soil aggregates, AMF community and aggregates were measured using Illumina MiSeq high-throughput sequencing and wet screening methods in red soil of sloping farmland. The AMF community and its relationship with soil factors and aggregate stability were studied under the four treatments of vetch rotation corn (V-C), pea rotation corn (P-C), winter fallow corn (F-C), and annual fallow (F-F). The results showed that the aggregate content of >2 mm, R0.25, and MWD in the F-F, V-C, and P-C treatments were significantly higher than those in F-C (P<0.05), and the aggregate content of <0.25 mm was significantly lower than that of F-C (P<0.05). The ACE, Chao1, and Shannon indexes of the F-F treatment were 29.56%, 35.78%, and 45.55% higher than those of the F-C treatment, respectively. Glomus was the dominant genus of AMF communities under all treatments, whereas Scutellospora showed a significant difference among the treatments (P<0.05). PCoA analysis showed that PC1 and PC2 together explained 29.99% and 22.40% of the difference in the AMF community composition, respectively. The correlation analysis showed that there was a significant negative correlation between Scutellospora and alkaline nitrogen (AN) and organic matter (SOM) (P<0.05), a significant positive correlation between Scutellospora and available potassium (AK) (P<0.05), and a significant positive correlation between Glomus and alkaline nitrogen (P<0.05). RDA analysis showed that AMF diversity (Shannon index) and Scutellospora were significantly and positively correlated with aggregate content >2 mm and 2-1 mm, respectively (P<0.05). Therefore, annual fallow and vetch rotation corn were conducive to improving the stability of soil aggregates and changing the composition of the AMF community. The research results provide a theoretical basis and reference for the annual rotation system to improve soil quality and implement a reasonable crop rotation and fallow pattern in southern China.

Effects of plastic film mulching and legume rotation on soil nutrients and microbial communities in the Loess Plateau of China

BackgroundPotato (Solanum tuberosum L.) continuous cropping causes the decrease of tuber yield, deterioration of quality and soil degradation in the semi-arid area. These negative effects can generally be mitigated by legume rotation and mulching. However, little is known about how can mulching and legume rotation alleviate the above damage through altering soil environment.MethodsA field experiment was conducted to investigate changes in soil properties and microbial community in response to legume rotation and mulching under six planting patterns: potato continuous cropping without film mulching (PC), potato continuous cropping with film mulching (PCF), potato–broad bean rotation without film mulching (R1), potato–broad bean rotation with film mulching (R1F), potato–pea rotation without film mulching (R2) and potato–pea rotation with film mulching (R2F).ResultsCompared with the PC, the R1F and R2F had significantly enhanced the contents of alkaline nitrogen (AN), available phosphorus (AP), available potassium (AK), total carbon (TC) and total nitrogen (TN), but reduced soil pH and electrical conductivity (EC). The Shannon index of fungi in R1F and R2 was significantly higher than other treatments. The dominant bacterial and fungal phyla of each treatment was Proteobacteria and Ascomycota. R1, R1F, R2 and R2F enhanced the relative abundance of metabolic fungi and altered key differential microbial species. Soil EC, AN and AK were major factors influencing the soil bacterial and fungal communities.ConclusionOverall, the study demonstrated that potato-broad bean/pea rotation with mulching can be adopted as the preferred cropping systems to alleviate potato continuous cropping obstacles through enhancing soil fertility and regulating soil microbial communities in the semi-arid of Loess Plateau, China.Graphical

The impact of no‐till crop rotation on dryland soil properties and crop yields

AbstractInformation on the effect of no‐till crop rotation on a broad range of soil properties and long‐term crop yields is needed to evaluate its benefits on ecosystem services compared with monocropping. The objective of this study was to examine the effects of no‐till crop rotation (barley [Hordeum vulgare L.]/spring wheat [Triticum aestivum L.]–pea [Pisum sativum L.]) and monocropping [continuous barley/spring wheat] on 66 dryland soil physical, chemical, biological, and biochemical properties and long‐term crop yields at two dryland farm sites (14‐ and 36‐yr old) in the northern Great Plains. Soil samples collected to a depth of 15 cm in April 2019 were analyzed for soil properties and crop yields determined. At the long‐term site, crop rotation increased 11 properties, but reduced 16 of 66 soil properties compared with monocropping. At the short‐time site, crop rotation increased 6 properties, but reduced 13 of 66 soil properties compared with monocropping. Longer duration experiments showed more differences in soil properties due to crop rotation than shorter duration experiments. Spring wheat and barley yields were greater following pea than following spring wheat or barley during years with normal or above‐average precipitation at both sites. Pea yield in the crop rotation was also greater during these years. Barley/spring wheat–pea rotation can enhance some soil properties and dryland crop yields compared with continuous barley/spring wheat during wet years in the semiarid region of the northern Great Plains.

The effect of nitrate nitrogen on barley yield on chernozem of the southern steppe zone of the Southern Urals

Increasing the yield of barley cultivated in crop rotations and by sowing permanently is a major problem in the steppe zone of the Southern Urals. This requires to study factors affecting an increase in the crop yield. The aim of the study is to identify the effect of nitrate nitrogen, the biological activity of soil and the aftereffect of predecessors on barley productivity at different levels of mineral nutrition. In the experiment, methods such as field, ionometric and decomposition of flax fiber were used. The methods used make it possible to obtain new original results on the factors and experimental options. Over 18 research years, the highest barley yield was observed in millet and pea rotation using fertilizers. It amounted to 1.42 and 1.43 tons per 1 ha. These results were achieved due to the consumption of nitrate nitrogen up to 2.3 mg and accumulation in the amount of 7.7 mg per 100 g of soil with an activity of microorganisms of 8.3 and 8.1 %. The results are of scientific and practical importance in the field of agriculture and crop production.

Land cover does not affect microbial and plant response to glyphosate and nitrogen application in the Pampas (Argentina)

Many complex, natural landscapes have been transformed into simpler agroecosystems by continuous cropping and the application of glyphosate and fertilizers. The current mosaic with different land cover types can harbor different soil microbial communities. Here, we investigated how the microbial community and ryegrass plants responded to glyphosate and nitrogen application to soils from four different cover types (soybean monocropping; wheat/soybean-field pea rotation, herbaceous- and woody- uncropped margins). We predict that soils from different land cover types will display different responses of their detritivore microbial communities and plant growth to herbicide and fertilizer application. All the studied variables differed among land cover types. Woody margins tripled the soil carbon content and the microbial respiration of herbaceous margins, although the later had more diverse soil microbial communities. Soils from soybean monoculture had higher respiration rates (37%) than those from crop rotation, where ryegrass accumulated lower biomass (12% lower). Despite these differences between land cover types, neither glyphosate nor nitrogen fertilization significantly influenced these properties. Only ryegrass plants growing on glyphosate-treated soils accumulated more biomass than the rest whereas they did not respond to nitrogen. These results suggest that glyphosate and nitrogen at recommended doses did not have a significant impact on the soil performance of the different types of cover.

Exploring the potential of using 7Be measurements to estimate soil redistribution rates in semi-arid areas: results from Western Iran and Southern Italy

The need for further research to investigate the possibility of using 7Be as a soil erosion tracer under a range of climatic conditions, specifically in arid and semi-arid agro-environments, has been emphasised in the literature. In this context, this paper reports research conducted in two semi-arid areas located in Western Iran and Southern Italy in order to assess the potential of using 7Be measurements for estimating soil erosion over short timescales. The two study sites differ in terms of land use. More specifically, the area in Western Iran, under cultivation, is cropped mostly under wheat, barley and pea rotation. The area in Southern Italy has never been cultivated, has few eucalyptus trees, resulting from re-afforestation conducted in 1966 and retains a sparse grass cover. Soil sampling required two field campaigns undertaken in April 2011 and April 2016 in Western Iran and Southern Italy, respectively. In Western Iran, the 7Be reference inventory was estimated at 326 ± 40 Bq m−2 and the corresponding value of the shape factor was equal to 3.57 kg m−2. The soil loss was calculated to be 6.8 Mg ha−1, resulting in a Sediment Delivery Ratio (SDR) of ca. 80%. In Southern Italy, the 7Be reference inventory was equal to 180 ± 20 Bq m−2, emphasising a lower penetration of 7Be into the soil that is documented by a lower value of the shape factor (2.45 kg m−2). The overall results provided a net soil loss of ca. 20.7 Mg ha−1. In this case, no deposition was documented and a SDR value of ca. 100% was calculated. The magnitude of soil erosion reflects, for both sites, the steep topography, the different management system and the heavy rainfall occurring during a period that coincides with the absence of vegetative cover. The results obtained in this study are in line with similar studies carried out in other countries and suggest that, in cultivated areas, care must be taken when traditional cultivation systems are applied; in re-afforested areas, the presence of a uniform vegetative cover is crucial in protecting soil from erosion. However, there still is a need for further work to assess the feasibility of using 7Be in different areas and under different land uses or vegetation covers. Also, further refining of the conversion model, which is based here on the simple exponential function, are still possible.

A Comparative Study of Rotation Patterns on Soil Organic Carbon in China’s Arid and Semi-Arid Regions

The practice of crop rotation can significantly impact carbon sequestration potential. In exploring whether crop rotation has the potential to improve soil carbon sequestration in China’s Loess Plateau, soil organic carbon (SOC), soil water content (SWC), soil bulk density (SBD), and soil pH were compared across the 0–1.0 m soil profile, under four crop rotation patterns: lentil–wheat–maize, wheat–potato–lentil, wheat–maize–potato, and wheat–flax–pea. The lentil–wheat–maize and wheat–maize–potato rotations have been practiced over the past 20 years, while the wheat–potato–lentil and wheat–flax–pea rotations were established in 1978 (~40 year rotations). The results showed that under the 20-year lentil–wheat–maize rotation, SOC was not significantly different to that of the wheat–maize–potato rotation, at 6.81 g kg−1 and 6.91 g kg−1, respectively. However, under the lentil–wheat–maize rotation, SWC (9.81%) and SBD (1.19 Mg m−3) were significantly higher, but soil pH (8.42) was significantly lower than the same metrics under wheat–maize–potato rotation (8.43% and 1.16 Mg m−3, and 8.50, respectively). For the 40-year rotations, SWC (9.19%) and soil pH (8.41) under the wheat–potato–lentil were not significantly different to that of the wheat–flax–pea (8.87%, and 8.40, respectively). SOC (6.06 g kg−1) was significantly lower, but SBD (1.18 Mg m−3) was significantly higher under the wheat–potato–lentil than the wheat–flax–pea (7.29 g kg−1, and 1.15 Mg m−3, respectively) rotations. Soil carbon sequestration for the lentil–wheat–maize and wheat–potato–lentil rotations was co-influenced by SWC, SBD, and soil pH, while for wheat–maize–potato and wheat–flax–pea rotations, it was co-influenced by SWC and soil pH. The economic value of the four studied crops is, in order: potato &gt; maize &gt; wheat &gt; flax. The results of the present study suggest that the lentil–wheat–maize and maize–flax–pea rotations are the most suitable patterns to optimize simultaneous economic and ecological development of the study area.

Soil inorganic carbon under no‐till dryland crop rotations

AbstractSoil inorganic carbon (SIC) constitutes a large proportion of soil total carbon (STC) under dryland cropping systems in arid and semiarid regions. Information on the effect of management practices on SIC is scarce. We evaluated the effect of 1‐ to 4‐yr no‐till diversified crop rotations on SIC at the 0‐ to 120‐cm depth in Sidney and Friod, MT. The SIC increased from the soil surface to 90‐cm depth and then declined. Crop rotations did not affect SIC and STC, except at 90–120 cm in Sidney where barley (Hordeum vulgare L) and winter wheat (Triticum aestivum L) in rotation with pea (Pisum sativum L.) had higher SIC than other crop rotations. The SIC contributed from 0% of STC at 0–15 cm for most crop rotations to 78% at 60–90 cm for barley–pea rotation. Long‐term studies are needed to evaluate the effect of dryland crop rotations on SIC in the northern Great Plains.

Changes in soil chemical properties and crop yields with long‐term cropping system and nitrogen fertilization

AbstractInformation is needed on the long‐term impact of cropping system and N fertilization on dryland soil health and crop yields. We studied the 13‐yr effect of cropping system and N fertilization rate on soil chemical properties at the 0‐ to 60‐cm depth and related them to annualized crop yield in the northern Great Plains. Cropping systems were conventional tillage barley (Hordeum vulgare L.)/spring wheat (Triticum aestivum L)–fallow (CTB/WF), no‐tillage barley/spring wheat–fallow (NTB/WF), no‐tillage barley/spring wheat–pea (Pisum sativum L) (NTB/WP), and no‐tillage continuous barley/spring wheat (NTCB/W). Nitrogen fertilization rates were 0, 40, 80, and 120 kg N ha−1 to barley planted from 2006 to 2011 and 0, 50, 100, and 150 kg N ha−1 to spring wheat planted from 2012 to 2018. At 0 to 5 cm, soil pH and CEC were greater with NTB/WP than NTCB/W and CTB/WF, and soil organic matter (SOM) and Olsen‐P were greater with NTCB/W than CTB/WF. Increased N rate reduced soil pH, K, Ca, Mg, and CEC at most soil depths. Annualized crop yield was greater with NTCB/W and NTB/WP than NTB/WF and CTB/WF and maximized at 80–100 kg N ha−1. Most soil chemical properties induced by N fertilization were negatively correlated, but Mg concentration at 30–60 cm induced by cropping system was positively correlated with annualized crop yield. No‐till barley/spring wheat–pea rotation with 80–100 kg N ha−1 can sustain dryland soil chemical properties and barley and spring wheat yields in the northern Great Plains.

Crop performance, biological N fixation and pre-crop effect of pea ideotypes in an organic farming system

Pea (Pisum sativum L.) is a valuable grain legume in organic crop rotations. Pea rotations provide nitrogen (N) to the system through N fixation and produce animal feed or human food. Because of the high susceptibility of pea to pests, diseases and weeds and due to low profitability, especially in organic systems, pea cropping intensity decreased in the last 15 years in Austria. Therefore, it is important to find strategies for improving pea cropping systems in organic systems, by increasing yields and providing a positive N balance. The objective of this study was to compare pea genotypes of selected field and fodder pea in pure and mixed pea stands for biomass performance, biological N fixation and pre-crop effect under dry site conditions in a 2-year study in Eastern Austria. Pea N fixation was estimated using the extended N-difference method, with oat as the reference crop. The highest grain yield was found for the leafed field pea, with 2.5 Mg dry mass (DM) ha−1, followed by the semi-leafless field pea with 2.1 Mg DM ha−1 and the pea-mixtures with 2.2 Mg DM ha−1. The field pea cultivars yielded more than the fodder pea cultivars with 1.6 Mg DM ha−1. The average N concentration in pea grains was 3.6 mg g−1. The fodder pea type contained 3.8 mg g−1, significantly more N (p < 0.0001) than the semi-leafless and leafed field pea. Pea N fixation ranged from 53 to 75 kg N ha−1, corresponding to 42–50% of N derived from the atmosphere (% Ndfa). No differences in N fixation were found among cultivars, types and field/fodder pea. The fodder pea exported less N from the field because of their lower grain yield. Therefore, the N balance (N-input − N-output) of fodder pea was positive, with + 3.4 kg N ha−1 compared to the negative N balance of − 0.6 to − 3.6 kg N ha−1 for the leafed field pea types. These differences were not reflected in the following winter wheat crop, where the DM grain yield was 3.6–3.9 Mg ha−1 with no differences between cultivars and ideotypes. The results demonstrate that leafed field pea could have a sufficient grain yield and fodder pea could produce high N concentration in the grains. Because there are no differences regarding the effect of pea types on the yield of the following crop, it can be concluded that all tested pea types are suitable for successful organic pea production under dry site conditions. While there were no negative effects on the subsequent crop, the different ideotypes and mixtures may be selected based on different management goals.

Productivity, economic performance, and soil quality of conventional, mixed, and organic dryland farming systems in eastern Washington State

The global trends of shortening crop rotations, simplifying cropping systems, and segregating livestock from cropping enterprises have generated high yields while creating high environmental costs. Diversification, including integrated crop/livestock systems and the use of cover, forage, and perennial crops, can be used to improve soil health, reduce financial risk, increase yields, and reduce many negative environmental externalities. With such diversification in mind, we conducted a 5-year study examining four contrasting farming systems in dryland eastern Washington State in terms of their impacts on total productivity, economic performance, and soil quality. The four systems were a conventional (CONV) winter wheat/spring wheat/spring pea rotation, typical for the area; a mixed crop-livestock (MIX) winter wheat/spring wheat/grazed winter pea forage rotation; an organic mixed crop-livestock (ORGcrop) rotation of 3 yr perennial alfalfa and grass/grazed pea forage/winter wheat; and an organic hay (ORGhay) continuous perennial alfalfa and grass system. Soft white winter wheat (SWWW) yields were higher following grazed pea forage in MIX (6.2 Mg ha−1) than following harvested pea crop in CONV (5.9 Mg ha−1) despite lower N fertilizer rates in MIX. Following 3 yr of alfalfa and grass hay and no N fertilizer, SWWW yields in ORGcrop (6.2 Mg ha−1) were similar to CONV and MIX yields but averaged 15.5% lower protein concentration. Over the 5-yr rotation, average net returns were ORGhay ($616 yr−1) > ORGcrop (216 yr−1) > MIX (−1 yr−1) = CONV (−13 yr−1), in part due to high hay prices and average grain prices during this period compared to long-term averages. Over the course of the study, total soil profile SOC showed significant negative trends in CONV (−3.1 Mg C ha−1 yr−1) and MIX (−4.1 Mg C ha−1 yr−1) but not in ORGcrop and ORGhay. In surface (0–15 cm) soil, microbial biomass carbon and nitrogen and beta-glucosidase activity were greater in ORGcrop and ORGhay than in CONV and MIX. The landscape position of this study site is of relatively poorer soil quality and results may differ across the heterogeneity of a whole farm field. Overall, ORGhay, ORGcrop, MIX, and CONV in this order produced a gradation of forage production relative to cereal production from greatest to least, and also a gradation of economic and soil sustainability metrics from greatest to least. This study found that integrating perennial crops, such as alfalfa and forage grasses, into organic farming systems can build soil quality, be profitable, and supply nitrogen to succeeding grain crops.

Micronutrient Concentrations in Soil and Wheat Decline by Long-Term Tillage and Winter Wheat–Pea Rotation

Tillage plays a major role in nutrient dynamics under dryland cropping systems, but there remains uncertainty regarding the long-term impacts of tillage on nutrient availability. The objective of this study was to examine the influence of tillage intensity and timing on micronutrient concentration of soils and winter wheat (Triticum aestivum L.) under dryland winter wheat–pea (Pisum sativum L.) or WW-P rotation. The treatments included moldboard tillage in fall (FT) and spring (ST), disk/chisel tillage (DT), and no-tillage (NT). The concentrations of Mehlich III extractable boron, manganese, zinc, copper, and iron in soil were unaffected by the tillage methods; however, a significant decline in extractable zinc in the top 10 cm soil was observed compared to an adjacent undisturbed grass pasture (GP) (NT: 2.3 mg kg−1 vs. GP: 6.0 mg kg−1). In the upper 10 cm soil surface, NT (123 mg kg−1) maintained the extractable manganese concentration with GP (175 mg kg−1) whereas FT (97 mg kg−1), ST (92 mg kg−1), and DT (113 mg kg−1) had lower manganese than GP. Soil pH declined in the upper 10 cm under NT more than in the rest of the WW-P treatments. The results suggest NT can play a vital role in sustaining micronutrient availability due to decreased soil pH and the greater amount of organic matter within the surface soil of NT compared to other tillage methods.

Bacterial and fungal diversity in rhizosphere and bulk soil under different long-term tillage and cereal/legume rotation

Soil microbial diversity is important in maintaining soil quality, sustainable agriculture, and ecosystem function. Soil management practices can influence the diversity and activity of soil microbes in agricultural fields. The objective of this study was to assess the effects of tillage and stubble management on the diversity of bacteria and fungi, chemical property and total carbon emission in the rhizosphere and bulk soils in wheat (Triticum aestivum L.) -pea (Pisum arvense L.) rotation at pre-harvest. Treatments included conventional tillage with stubble removed (T), no-tillage with stubble removed (NT), conventional tillage with stubble incorporated (TS), and no-tillage with stubble retained (NTS). Bacteria 16S rRNA (V3V4) and fungi ITS (ITS2) region genes were sequenced from bulk soil and rhizosphere soils. Abundance of the dominant bacterial (Actinobacteria, Proteobacteria, Chloroflexi, Acidobacteria, and Planctomycetes) and fungal (Ascomycota and Basidiomycota) phyla identified did not differ significantly (P < 0.05) among treatments. Rhizobium and rare fungi Kurtzmanomyces occurred in the rhizosphere but were virtually absent in bulk soil. However, bacterial and fungal OTUs diversity indices were less in the rhizosphere compared to bulk soil. Soil from the NTS and NT had the greatest bacteria 16S rRNA and fungi ITS region number of OTUs; however, the microbial community did not differ among treatments. The abundance of class level bacteria and fungi were associated with soil pH, total organic carbon, total nitrogen, NH4+ -N, and NO3¯ -N contents. The results indicate that bulk soil had higher microbial library, which will be beneficial for establishment of the next season’s microbial community.

Effect of tillage on macronutrients in soil and wheat of a long-term dryland wheat-pea rotation

Tillage is known to significantly affect crop residue decomposition and soil nutrient dynamics, but the impacts of tillage on soil and plant macronutrients concentration with time have not been reported. This study was conducted (i) to assess the influence of tillage timing and intensity on soil and wheat (Triticum aestivum L.) macronutrient concentration of a winter wheat-dry pea (Pisum sativum L.) rotation (WW-P) under a dryland cropping system, and (ii) to compare macronutrients in the tillage treatments with a nearby long-term grass pasture (GP). The tillage treatments were fall tillage (FT), spring tillage (ST), no-tillage (NT) and disk/chisel tillage (DT/CT). Soil samples from 1995, 2005, and 2015 were analyzed to determine the concentration of soil organic carbon (SOC), total N and S, Mehlich III extractable P, K, Ca, and Mg, and soil pH. The impact of tillage on soil macronutrient concentration was evident after 52 years of WW-P. As a result, greater concentration of SOC, total S, and extractable P, and K were observed under NT than under FT or ST. The WW-P plots lost 28, 46, and 67% of SOC, Mg, and S, respectively, in the top 10 cm of soil compared with the GP plots, whereas the NT plots were the only plots in WW-P to maintain a P concentration (99 mg P kg−1) comparable with GP plots (102 mg P kg−1) at the same depth. The results indicated that NT could be beneficial to recharge the soil nutrient pool over time compared to FT or ST.

Evaluation of bacterial and fungal diversity in a long-term spring wheat – field pea rotation field under different tillage practices

Soil management practices have the potential to modify the diversity and function of microbes in agricultural fields. The aim of this study was to investigate bacterial and fungal diversity in a 15 yr wheat–pea rotation tillage experiment. The treatments included conventional tillage with stubble removed, no-till with stubble removed, no-till with stubble retained (NTS), and conventional tillage with stubble incorporated. Illumina high-throughput sequencing platform was employed to sequence bacteria 16S rRNA (V3V4) and fungi internal transcribed spacer (ITS2) region genes in 0–10 cm and 10–30 cm of soil sampled. The dominant bacterial and fungal phyla identified at 97% similarity cutoff across both depths of treatments were Proteobacteria (26.3%), Actinobacteria (25.1%), Acidobacteria (15.0%), Gemmatimonadetes (8.8%), Ascomycota (85.8%), and Basidiomycota (8.0%). NTS had significantly (p &lt; 0.05) higher microbial diversity indices, total organic carbon, soil microbial biomass carbon and nitrogen, NO3-N, and NH4-N at 0–10 cm depth. Tillage and stubble effects had a significant correlation with some phyla such as Proteobacteria, Actinobacteria, Gemmatimonadetes, JL-ETNP-Z39, Nitrospirae, Chloroflexi, Firmicutes, and other identified and unidentified minor microbial phyla. No-till and residue retention practices influenced fungal and bacterial species diversity through improved soil chemical properties, which have potential to affect the habitat and activity of soil microbes. Therefore, no-till and stubble retention could improve soil quality and promote sustainable agriculture in the rainfed Loess Plateau.

Location-dependent impacts of liming and crop rotation on bacterial communities in acid soils of the Pacific Northwest

The cropping systems of northern Idaho and eastern Washington are dominated by a cereal-based (winter wheat) rotation that is exclusively rainfed. Following the green revolution, the productivity of wheat increased dramatically with semi-dwarf varieties and inexpensive synthetic fertilizers. However, long-term and frequent use of ammonium-based nitrogen fertilizers has resulted in the gradual acidification of fields in the region, with reduced productivity and symptoms of aluminum toxicity in some locations. A micronized liquid formulation of lime (calcium carbonate) was evaluated at three locations to mitigate soil acidification in comparison to a no-lime control. To examine how liming affects bacterial community structure, soil samples were taken in the spring in wheat and pea rotations 7 and 19 months after lime application, DNA was extracted and the V1-V3 portion of the 16S rRNA gene was amplified and sequenced with Illumina MiSeq. pH was only increased ∼0.2–0.3 units in most locations, and liming only had a significant effect on bacterial community composition at one location (Pullman). Liming had no consistent or significant effect on community richness or diversity. Location had a stronger effect on communities than liming or crop rotation, but some specific taxa increased in relative abundance in response to liming, including the families Cytophagaceae and Flavobacteriaceae (Phylum Bacteroidetes), A4b (Phylum Chloroflexi), and Opitutaceae (Phylum Verrucomicrobia). A number of operational taxonomic units (OTU) in Chitinophagaceae and Xanthomonadaceae were increased by liming at the Pullman location, which had 3–4 X more OTUs affected by liming than the other locations. Streptomycetaceae and Oxalobacteraceae were more abundant in root zone soil of wheat than pea. In conclusion, there was a strong interaction between liming and location in determining soil bacterial composition, but specific components of the bacterial community responded to even minimal increases in soil pH.

Long‐Term Crop Rotation Effects on Production, Grain Quality, Profitability, and Risk in the Northern Great Plains

Core Ideas Diversified rotations are more productive and profitable than cereal only rotations. Fallow rotations are less profitable than continuous cropping in the Northern Plains. Continuous cropping is riskier; however, it is preferred when averse to risk. Crop production in the semiarid Northern Great Plains has historically been limited to wheat (Triticum aestivum L.), with fallow every second or third year. In response to current prices and new production technologies, these cropping systems have been replaced with reduced frequency of fallowing and inclusion of oilseed and pulse crops in the rotation. This study examined the long‐term changes that producers can expect in their production levels and economic returns for five wheat‐based rotations with different fallow frequencies, use of an annual legume green manure to partially replace fallow, and a continuous diversified rotation of cereal–oilseed–cereal–pulse crops. The findings were based on the last 11 yr of a 28‐yr (1987–2014) crop rotation experiment performed at Swift Current, SK, Canada. Despite the higher grain yield on fallow versus stubble, total grain production increased as fallow frequency decreased. The continuous wheat rotation produced 21% more wheat than the rotations with fallow. Wheat protein was highest for the rotation containing the legume green manure. Since its establishment in 2003, a wheat–canola (Brassica napus L.)–wheat–dry pea (Pisum sativum L.) rotation was more profitable than the traditional wheat systems. Participation in a crop insurance program reduced the financial risk from low crop yields, particularly for continuous cropping. We concluded that under current economic conditions and production practices, producers can indeed enhance production levels and farm profitability with adoption of more intensive (reduced fallow) crop rotations, particularly those that also include oilseed and pulse crops.