Crop Rotation Treatments Research Articles

From complex histories to cohesive data, a long-term agricultural dataset from the Morrow Plots

Long-term agricultural experiments are essential to measure the impacts of farming practices on crop yields, soil fertility and biogeochemical processes. However, these impacts often only manifest at decadal timescales, requiring committed and consistent data collection that exceeds the timelines for most experiments. The second oldest agricultural experiment in the world, the Morrow Plots at University of Illinois Urbana-Champaign (USA) has examined the impact of crop rotation and fertility treatments on maize (Zea mays L.) yields since 1876. While results have been widely reported since 1888, the publicly available longitudinal dataset described here now allows for validation of those past results, as well as new analyses and investigations. A multi-disciplinary team identified, collected, and aggregated multiple historical data sources into one comprehensive and FAIR (Findable, Accessible, Interoperable and Reusable) dataset that synthesizes yield data and management practices from 1888–2021. Updated versions of the dataset will continue to be published as additional data from this ongoing experiment are made available and as new historical data sources are uncovered.

Mycorrhizal Fungal Inoculum Potential in Crop Rotation Soil With Different Levels of Irrigation

Research indicates arbuscular mycorrhizal fungi (AMF) inoculum potential and AMF biomass production in agricultural soil are strongly influenced by both soil moisture availability and crop rotation (CR) strategies. We hypothesized that AMF biomass production in and inoculum potential of Wyoming semiarid agricultural soil would increase when managed using CR and irrigation. To test this hypothesis, we examined AMF activity (AMF biomarker fatty acid, and AMF infection of roots) in two differently managed soils (no-CR soil and two-year CR soil) in a field experiment. Furthermore, in a greenhouse experiment, we examined AMF activity in the same two CR treatment soils under different irrigation regimes (wet, irrigated to 60% field capacity, and dry, irrigated to 15% field capacity). Notably, the two-year CR soil had greater amounts of AMF biomarker fatty acid and greater inoculum potential, and higher percentage of AMF root colonization compared to no-CR soil. Despite the fact that the CR soil had more AMF propagules, it was less than the undisturbed non-agricultural native sage-grassland soils previously reported. Overall, the findings suggest that high levels of irrigation can inhibit the activity of AMF adapted to semiarid soil conditions and CR can increase activity of AMF in soils from semiarid regions.

Tillage and cover cropping influence phosphorus dynamics in soil and water pools

AbstractWinter cover crops (CCs) have the potential to reduce phosphorus (P) loss by temporarily fixing P into CC biomass. A field experiment with no‐tillage (NT) and conventional tillage (CT) was used to study the ability of different CC species planted after corn (Zea mays L.) and soybean (Glycine max L.) harvests to reduce the P availability in soil solution. The effect of three crop rotations (corn–no CC–soybean–no CC [C–S], corn–cereal rye (Secale cereale)–soybean–hairy vetch (Vicia villosa) [C–R–S–HV], corn–cereal rye–soybean–oats (Avena sativa)+ radish (Raphanus sativus L.) [C–R–S–OR]) and two tillage (NT and CT) treatments was determined on soil available P and soil solution P content through pan (A horizon) and tension (100‐cm depth) cup lysimeters. The experiment was set up as a randomized complete block design with tillage as a split factor with three replicates. Over the study period, incorporating hairy vetch in C–R–S–HV rotation reduced the Mehlich‐3 P content in soil by 26%–29% compared to the C–S and C–R–S–OR rotation. Both CC rotations (C–R–S–HV and C–R–S–OR) were effective in reducing dissolved reactive P (DRP) concentration in pan and tension cup lysimeters compared to the C–S in both CT and NT systems. However, these results varied with CC species grown and seasonal variability in precipitation. A significantly lower DRP load with crop rotation and tillage treatments was observed mainly during the CC growing season. During the study period, crop rotations with reduced labile soil P content and DRP loss were ranked in an order of C–R–S–HV > C–R–S–OR > C–S. Overall, this study showed that CCs have the potential in both CT and NT systems to significantly reduce P in soil and soil solution, and these effects are resilient to a wide range of precipitation conditions.

First Report of Rhizoctonia solani AG1-IB Causing Tobacco Target Spot in China.

Tobacco target spot, caused by Rhizoctonia solani Kühn, induces shot-hole lesions on leaves that that significantly reduce yield and quality of tobacco. In July 2022, samples (n=5) with target spot were collected from three tobacco fields, one each in Puer (22.63°N, 100.72°E, cv. Yunyan87) and Mengzi (23.26°N, 103.36°E, cv. Yunyan87) of Yunnan province and one in Dandong (40.63°N, 124.18°E, cv. Liaoyan17) of Liaoning province, China; disease incidence in these fields was approximately 30%~40%. Initial symptoms (2- to 3-mm-diameter lesions) appeared on the middle to lower leaves, then expanded to 2 to 3 cm in diameter and developed the shot-hole appearance. Pieces of tissue (5×5 mm) were cut from the edge of lesions, surface sterilized, rinsed in sterile water, then placed on the surface of water agar (WA) and incubated at 25℃ for 2 days in the dark. Single hyphal tips were taken from fungal isolates identified as R. solani based on the morphological traits (Tsror 2010), then transferred onto potato dextrose agar (PDA) and cultured for 3 d as described above. A total of 15 pure cultures were obtained. With the exception of YN-3 (isolated from Puer), YN-62 (isolated from Mengzi) and LN-95(isolated from Dandong) strains, which exhibited hyphal fusion reaction with AG1-IB standard strain, all the other strains demonstrated hyphal fusion with AG-3 standard strain (Ogoshi 1987). Genomic DNA of these three strains were extracted by the CTAB method and ITS regions of rDNA were sequenced (White et al. 1990). The sequences were deposited in GenBank with accession No. OR770079, OR770080 and OR770082. All the three rDNA-ITS sequences exhibited 99.85% similar to AG1-IB found in GenBank, and a phylogenetic tree using a neighbor-joining method grouped the three strains within the R. solani AG-1 IB clade. Therefore, based on the hyphal fusion reaction and molecular methods, these isolates were identified as R. solani AG1-IB. To determine pathogenicity of the isolates, the healthy leaves of tobacco plants (cv. Yunyan 87) were used. Five-mm-diameter mycelial plugs of the strain on PDA were inoculated on leaves that had been previously wounded with a sterile needle, and cotton balls moistened with sterile water were used for moisturizing the inoculation sites. Ten leaves were inoculated for each strain and leaves inoculated with PDA plugs were as control. The experiment was conducted twice. All plants were incubated for 2 d at 15℃ to 25℃ and 90% relative humidity with a 12 h photoperiod/day. Irregularly shaped lesions appeared on the leaves around each of the inoculated sites, but not on control leaves. The pathogens were reisolated and confirmed be R. solani AG1-IB by hyphal fusion and molecular identification tests as previously described, thereby fulfilling Koch's postulates. It has been reported that AG-3, AG-2 (Mercado Cardenas et al. 2012), AG-5 (Wang et al. 2023) and AG-6 (Sun et al. 2022) of R. solani could cause tobacco target spot, but AG-3 is considered the main causal agent (Marleny Gonzalez et al. 2011). To our knowledge, this is the first report of AG1-IB causing tobacco target spot in China and worldwide. The AG1-IB strain has a wide host range including cabbage, mint, lettuce, beans, and rice (Gonzalez et al. 2006). The discovery poses a new challenge for the prevention and control of tobacco target spot, especially when contemplating disease management strategies such as crop rotation and fungicide treatments.

A Bayesian approach to analyzing long-term agricultural experiments

Effective and flexible statistical analyses are key to getting the most out of long-term experiments (LTEs). Here, we aim to introduce Bayesian analysis to the wider LTE community and show how the modelling process differs from traditional statistical analyses. Bayesian methods have become increasingly popular due to more flexibility in model development with better access to statistical software and sampling algorithms. Using Bayes' Theorem, model coefficients are estimated by incorporating any prior knowledge we may have on model terms. Including prior knowledge in this way requires a different estimating procedure for a fitted model. Bayesian model coefficients are usually sampled from thousands of samples from one or more runs of a Markov Chain. We present the use of Bayesian analyses through three examples. Example 1 illustrates a single regression with and without factors using the Broadbalk Long-Term Experiment, showing how the estimated model changes with more uncertainty in our prior knowledge of model coefficients. Example 2 demonstrates the use of multiple regression, predicting grain yield from factor variables and seasonal weather variables. Example 3 shows an estimation of soil carbon changes under crop rotation and fertilization treatments with a hierarchical time series model using a Swedish soil fertility experiment.

Influence of crop rotation, irrigation, fertilization, and tillage on the aggregate property and soil wind erosion potential in the floodplain of the Yellow River

The floodplain of the Yellow River (FPYR) is threatened by severe soil erosion. Soils are often susceptible to wind erosion owing to their coarse-textures and weak aggregation, yet studies are yet to describe the ability of soils to resist wind erosion in this region. Accordingly, this study aimed to quantify how soil wind erosion potential is affected by soil aggregate properties, such as dry aggregate geometric mean diameter (GMD), aggregate geometric standard deviation (GSD), aggregate stability, and soil bulk density, and to assess the effects of soil type, crop rotation, irrigation, fertilization, and tillage treatments on these aggregate properties in the main wind erosion area across the FPYR. Significant differences in GMD and aggregate stability were found between crop rotation treatments, whereas crop rotation marginally affected the soil bulk density. Further, the impact of management practices on aggregate properties differed for each soil type. The soil aggregate erodible fraction (EF) in the FPYR ranged from 1.14 to 82.73% across sites, with a mean of 26.14% across soil types and management practices, which was lower than that previously reported in other wind erosion regions. We incorporated these measured EFs into the Revised Wind Erosion Equation (RWEQ) to evaluate the wind erosion risk of the FPYR. The results indicated that the central FPYR was more susceptible to wind erosion than the other regions, although the total wind erosion potential in the FPYR was small. Adoption of soil conservation practices could help minimize wind erosion and improve atmospheric quality in the region.

Cover Crop and Crop Rotation Effects on Tissue and Soil Population Dynamics of Macrophomina phaseolina and Yield Under No-Till System.

The effects of crop rotation and winter cover crops on soybean yield and colony-forming (CFU) units of Macrophomina phaseolina, the causal agent of charcoal rot (CR), are poorly understood. A field trial was conducted from 2011 to 2015 to evaluate (i) the impact of crop rotation consisting of soybean (Glycine max [L.] Merr.) following cotton (Gossypium hirsutum L.), soybean following corn (Zea mays L.), and soybean following soybean over a 2-year rotation and its interaction with cover crop and (ii) the impact of different cover crops on a continuous soybean crop over a 5-year period. This trial was conducted in a field with 10 subsequent years of cover crop and rotation treatments. Cover crops consisted of winter wheat (Triticum aestivum L.) and Austrian winter pea (Pisum sativum L. subsp. sativum var. arvense), hairy vetch (Vicia villosa Roth), and a fallow treatment was evaluated with and without poultry litter application (bio-cover). Tissue CFU of M. phaseolina varied significantly between crop rotation treatments: plots where soybean was grown following cotton had significantly greater tissue CFU than plots following soybean. Poultry litter and hairy vetch cover cropping caused increased tissue CFU, though this effect differed by year and crop rotation treatment. Soil CFU in 2015 was substantially lower compared with 2011. However, under some crop rotation sequences, plots in the fallow treatment had significantly greater soil CFU than plots where hairy vetch and wheat was grown as a cover crop. Yield was greater in 2015 compared with 2011. There was a significant interaction of the previous crop in the rotation with year, and greater yield was observed in plots planted following cotton in the rotation in 2015 but not in 2011. The result from the continuous soybean planted over 5 years showed that there were no significant overall effects of any of the cover crop treatments nor was there interaction between cover crop treatment and year on yield. The lack of significant interaction between crop rotation and cover crop and the absence of significant differences between cover crop treatments in continuous soybean planting suggest that cover crop recommendations for midsouthern soybean growers may need to be independent of crop rotation and be based on long-term crop needs.

Effects of rotation and Bacillus on the changes of continuous cropping soil fungal communities in American ginseng

The continuous cropping obstacle is the main factor in leading to difficulty in American ginseng replanting. The dormant microbiota in the soil may be the cause of American ginseng disease and eventually caused continuous cropping obstacles, but there are few studies on the dynamic changes of soil microenvironment after American ginseng planting. In this study, we tracked short-term variation in physicochemical properties, enzyme activities, and fungal communities over time-series in soils with continuous cropping obstacle under crop rotation and probiotic Bacillus treatments. Furthermore, we examined the relationships between the important fungal compositions and the soil properties. The results showed that sucrase, cellulase, urease and acid phosphatase activities were significantly increased, while catalase and dehydrogenase were decreased with treatments time. Rotation treatment significantly affected the diversity, dissimilarity degree and species distribution of soil fungal community with continuous cropping obstacle over a short-term. Moreover, beneficial fungal biomarkers such as Cladorrhinum, Oidiodendron, and Mariannaea were accumulated at 48 h under rotation treatments. Almost all fungal biomarkers were negatively correlated with hydrolases and positively correlated with oxidoreductases and acid phosphatase under crop rotation treatments. This study suggested that compared to probiotic Bacillus, crop rotation can significantly affect soil fungal community structure, especially the enrichment of specific potentially beneficial fungal species. Our findings provide a scientific basis for understanding the dynamic changes of fungal communities and soil properties with continuous cropping obstacle of American ginseng in initial stage of soil improvement.

Soil health indicator responses to three years of cover crop and crop rotation in a northern semi-arid region, the Canadian prairies

Increasing crop diversity via cover cropping is considered a powerful strategy to improve soil health; thus, a better understanding of the impacts on soil is crucial. In northern semi-arid regions, cover cropping can be agronomically challenging due to growing condition limitations, and the paucity of cover crop data only exacerbates this challenge. Still, farmers are interested in adopting cover crops to reach their soil health goals. Our study addressed this gap by 1) comparing rotations with versus without cover crops; and 2) comparing different rotational treatments of perennial alfalfa, two-year ‘short’ rotations, to four-year ‘long’ rotations with and without cover crops. After three years, soil health indicators were measured at four sites across the Canadian prairies, including wet aggregate stability (WAS), soil pH, electronic conductivity (EC), evolved soil CO2, soil active C, soil organic carbon (SOC), total carbon (C), N2O production, inorganic N, soil protein, potential mineralized N (PMN), and total N. During a dry period which limited cover crop growth, the cover crops had limited impact on soil health indicators, except for a reduction in spring soil nitrate-N levels at two of the four sites. Surprisingly, the crop phase of the rotation had more differences on soil health indicators than the inclusion of cover crops, but the inconsistency of the changes made it difficult to draw clear patterns. Most notably, soil health indicators (and especially soil CO2) responded to crop rotation treatment. The perennial treatment produced 4.57–8.74 µg g-1 24 hr-1; whereas other rotation treatments respired 25–28%, 44–45%, 22–28%, and 35–36% less CO2. Overall, early indicators of soil health change tended to be related to dynamics of soil inorganic N cycling and CO2 evolution. Our results suggest that a longer-term period of cover cropping and greater biomass accumulation will be needed to substantially impact soil health in this semi-arid environment. Implementing more ‘perennialized’ crop rotations will benefit the early indicators of soil health change in a short timeframe.

Effects of Crop Rotation and Tillage on Winter Wheat Growth and Yield under Cold Dryland Conditions

To investigate responses of two winter wheat genotypes under different crop management systems (rotation and tillage), a split–split plot experiment was conducted based on a randomized complete block design (RCBD) with three replications during 4 years in Maragheh, Iran. Three crop rotation treatments [vetch–wheat (V–W), chickpea–wheat (C–W), and safflower–wheat (S–W)] were considered in main plots, three tillage treatments (conventional-tillage (CT), minimum-tillage (MT), and no-tillage (NT)) were located in subplots, and two winter dryland wheat genotypes (Baran and Azar2) were allocated in sub-sub plots. Results indicated that soil moisture content in NT was greater than that in MT and CT. The highest relative water content (RWC), normalized difference vegetative index (NDVI), stomatal conductance (gs), and transpiration rate (E) were obtained from the Baran genotype in the V–W rotation under NT. In the last year of the experiment, rainfall productivity in NT treatment improved by 32%, compared to CT. The Baran genotype had higher rainfall productivity in both MT and NT treatments with 0.71 and 0.70 kg m−3, respectively. Crop water requirement was not affected by crop rotation or tillage treatments. Maximum grain yields in V–W, C–W, and S–W rotations were recorded as 2231, 2105, and 1991 kg ha−1, respectively. With increasing soil moisture storage and improving rainfall productivity under full implementation of conservation agriculture components (after 4 years), grain yield of Baran and Azar2 improved in NT compared to that of CT by about 6–9% and 6–14%, respectively. Therefore, the application of V–W rotation with NT in cold dryland areas is recommended for developing of conservation agriculture system.

Forage sorghum grown in a conventional wheat–grain sorghum–fallow rotation increased cropping system productivity and profitability

Intensifying winter wheat ( Triticum aestivum)–grain sorghum [ Sorghum bicolor (L.) Moench]–fallow (W–GS–FL) crop rotation with annual forages can increase productivity and resource use efficiency. The objective of this research was to quantify the impact of increasing crop intensity by growing forages in a traditional W–GS–FL rotation on cropping system productivity, water use, precipitation use efficiency, and net income. The study was conducted at the Southwest Research-Extension Center near Garden City, Kansas, from 2013 through 2020. Winter wheat (W), grain sorghum (GS), forage sorghum (FS), and forage oats (FO, Avena sativa L.) were used to generate six crop rotation treatments. These rotation treatments interspersed with fallow periods (FL) were W–GS–FL, W–FS–FL, W/FS–GS–FO, W/FS–FS–FO, W/FS–GS–FL, and W/FS–FS–FL. A W/FS indicates winter wheat double crop FS planted in the same year. The yield of FS was 45%–56% more with W/FS–FS–FO and W/FS–FS–FL compared with W–FS–FL. Available soil water at GS planting was 23%–30% less, and GS yield was 52%–60% smaller with W/FS–GS–FL compared to W–GS–FL. Water productivity and pre-season soil water storage were greatest with W/FS–FS–FL and W/FS–FS–FO. Inclusion of W/FS increased cost of production compared with W–GS(FS)–FL rotations. Gross return was greatest with W/FS–FS–FO and W/FS–FS–FL. The W/FS–FS–FO increased cropping intensity, productivity, resource use, and gross margin relative to other rotations in the semi-arid Great Plains. Producers should consider double-cropping of FS after wheat harvest, followed by a second year of FS in dryland cropping systems if there is sufficient forage demand.

Crop yield and water use efficiency in response to long-term diversified crop rotations.

Crop production and water productivity may be impacted by diverse crop rotation and management practices. A field study was conducted from 2017-2020 in the Loess Plateau to evaluate the effects of crop rotation sequences on pre-planting and post-harvest soil water storage (SWS), annualized crop yield, water use, and water productivity. Crops in rotation included oil flax (Linum usitatissimum L.) (F), wheat (Triticum aestivum L.) (W), potato ( Solanum tuberosum L.) (P). Twelve 4-year-cycle crop rotation treatments, along with a continuous oil flax treatment as a baseline, were included. The results showed that the average soil water content under the 0-150 cm soil layer in all treatments was increased after one rotation cycle, and the PWFW treatment achieved the highest SWC (17.1%). The average soil water storage (winter fallow season) and evapotranspiration (ETa) (growing season) under different crop rotation sequences were lower than those under continuous oil flax cropping. The ETa of FFFF increased by 28.9, 2.7, 15.3, and 28.4%, compared to average crop rotations in 2017, 2018, 2019, and 2020, respectively. Crop rotation had a significant effect on average annual yield and water use efficiency (WUE), which varied by year and rotation sequence. The crop rotations with the highest grain yield of oil flax were FFWP (2017), WFWP (2018),WPFF (2019) and FWPF (2020); the grain yield of wheat was highest when the two pre-crops (previously cultivated crops) were F-F, and potato yield was highest when the two pre-crops were W-F (except 2018). On average, the WUE of oil flax was 8.6, 38.7, 22.7, and 42.1% lower with FFFF than other diversity crop rotations in 2017, 2018, 2019, and 2020. We found that the WUE was not the largest when the grain yield of oil flax and wheat was highest. The treatments with maximum grain yield and WUE were not consistent. Our findings also revealed that wheat-potato-oil flax or potato-wheat-oil flax rotation could increase oil flax grain yields while wheat-oil flax-potato-oil flax markedly improved oil flax WUE.

Primary infection of onion downy mildew on onion seedlings caused by belowground Peronospora destructor inoculum containing germinable oospores

AbstractThis study investigated the possible role of oospores in soil as a primary source of onion downy mildew caused by Peronospora destructor. Oospores were extracted from the debris of diseased leaves collected in spring and stored outdoors during the summer. The resulting oospore suspensions were used for germination assays and inoculation experiments in the laboratory. Germination of oospores buried in the soil in cups occurred at a rate of approximately 0.3%–1.3%. Oospore suspensions were dripped or injected into artificial culture soil in cups at sowing onion seeds or at the seedling stage. After raising these plants in a growth chamber for more than 40 days, approximately 20%–30% of the plants exhibited leaf chlorosis and distortion, reproducing the primary infection symptoms of onion downy mildew observed in commercial fields. The presence of P. destructor in symptomatic plants was confirmed by histological observations and species‐specific PCR. Thus, laboratory experiments have demonstrated for the first time that (i) P. destructor oospores that have oversummered outdoors germinate in soil and (ii) belowground inoculum containing germinable oospores causes primary infection. The results showed that P. destructor survives as oospores during host‐free periods and can be a primary inoculum source for downy mildew during the following growing season in autumn. This research on soil‐borne primary infection by P. destructor may help develop knowledge‐based disease management strategies for onion downy mildew, such as proper disposal of crop residues after harvest, effective crop rotation and chemical soil treatments.

Performance of the single‐event wind erosion evaluation program (SWEEP) model in assessing the impact of crop rotation, green manure, fertilizer, and tillage on wind erosion

AbstractAgricultural land management strategies have been applied to minimize wind erosion in the inland Pacific Northwest (iPNW) due to their profound influence on various soil properties and crop residue characteristics. However, simulating soil loss in response to these treatment strategies remains a challenge. The objective of this study was to test the performance of the single‐event wind erosion evaluation program (SWEEP) in simulating soil loss from agricultural land under contrasting tillage, crop rotation, fertilizer, and green manure treatments in the iPNW. These management strategies appeared to impact residue characteristics but had little or no impact on soil properties except tillage treatments in the short term (<2 years). Tillage appeared to have a greater impact on soil properties and residue characteristics than other treatments. As a result, the performance of SWEEP varied among disk‐tillage (DT), undercutter‐tillage (UT), and NT (no‐tillage/zero‐tillage) treatments. No or little difference was found in the performance of SWEEP between winter wheat‐summer fallow (WW‐SF) and WW‐oilseed‐SF (WW‐O‐SF) crop rotations and synthetic and biosolids fertilizer treatments. In addition, the performance of SWEEP was acceptable for both crop rotation and fertilizer treatments. In contrast, poor agreement between simulated and measured erosion was found for manure treatments in which SWEEP over‐estimated erosion by 313 and 210% for no manure and manure treatments, respectively. The over‐estimation of SWEEP may be due to the over‐estimation of abrasion flux from the fully crusted soil surface. Our results suggest that SWEEP can be used to identify control measures for windblown soil loss in the iPNW.

Prevention and practical strategies to control mycotoxins in the wheat and maize chain

Within this study, food safety management systems for wheat and maize, and derived white wheat flour and maize flour, have been evaluated, considering different prevention and practical intervention measures to be applied during storage and processing. For this purpose, through an operational flow chart, authors have performed mycotoxin-hazard analysis in the pre- and post-harvest phases and applied Food Safety Objective (FSO) and Performance Objective (PO) concept. Mycotoxin-hazard and analysis of control measures in the pre-harvest operations indicated that the most important practices at pre-harvest level for the control of mycotoxins in wheat/maize chain may include: (i) land preparation, such as tillage, cover crop and crop rotation, (ii) planting and antifungal mulch treatment, application of botanical extracts and intercropping, (iii) application of fungal biocontrol agents to reduce aflatoxins and (iv) application of fungal and bacterial biocontrol agents. For the post-harvest operations one Critical Control Point (CCP) and five Control Points (CPs) have been determined. The CCP includes an intervention measure that can be applied during storage, such as the application of treatments with volatile bioactive compounds, cold plasma, ozonisation or UV treatment. The results of FSO/PO analysis applied to wheat/maize chain revealed that FSO (the maximum level of mycotoxins in final food products given in European legislation) could be reached by combining conventional production steps such as cleaning and milling with different intervention strategies. For all strategies presented here, application on actual food production site must take into account local specificities and its interaction with climatic conditions. • Mycotoxin-hazard analysis for pre- and post-harvest operations for wheat and maize. • Intervention measure during grain storage as potential critical control point. • Combination of cleaning and milling with intervention measures to reach food safety objectives.

Productivity improvement of bread wheat (Triticum aestivum L.) through crop rotation and organic matter application in degraded crop farms of Ethiopian highlands

AbstractBread wheat is one of the most important staple crops in Ethiopia and it is largely produced by smallholder farmers in the highlands of the country. Its productivity is, however, very low below the world average mainly due to the dwindling of soil productivity and depletion of soil fertility as the result of complete removal of crop residues as well as abandoning of crop rotation and organic matter application. Hence, a 3 years experiment was conducted to study the productivity improvement of bread wheat through crop rotation and organic manure application in degraded crop fields of Ethiopian highlands. Both at station and on-farm sites, factorial combinations of five crop rotations (R1+ = bread wheat–clover–potato, R2+ = clover–bread wheat undersowing lupine–potato, R3+ = potato–clover–bread wheat, R4+ = bread wheat undersowing lupine–potato undersowing lupine–bread wheat and R5+ = lupine–potato undersowing lupine–bread wheat) and four manure application rates [M1 = control/without manure, M2 = 2.5 t ha−1 Sesbania green manure (SGM), M3 = 5 t ha−1 fresh cattle manure (FCM) and M4 = 2.5 t ha−1 SGM + 5 t ha−1 FCM] were laid out in a randomized complete block design with four replications. Crop rotation treatments with plus sign (+) indicated that crop residues and/or green manure of preceding crops were incorporated into the soil. Sole bread wheat crop (R1) without manure application (M1) in the first year (2013) was considered as the control and baseline of the study. Results of the study clearly showed that the interaction of R3+ and M4 in 3 years period (2013–2015) enabled to recover the highest grain productivity of bread wheat from 0.95 and 0.69 to 4.83 and 4.14 t ha−1 with the percentile increments of 408.42 and 500.00% at station and on-farm sites, respectively. Thus, long-term application of organic manure with moderate quantity and incorporation of crop residues in pragmatic crop rotation of a vigorous legume before wheat have great potentials for recovering the productivity of bread wheat in degraded crop fields.

Organic soil fertility amendments enhance surface-dwelling beetle diversity in a sub-humid tropical environment under conservation agriculture

ABSTRACT Surface-dwelling beetles offer ecosystem services in agro-ecosystems including biological pest control and organic matter decomposition. This study was conducted to investigate beetle community response to six years of tillage, crop residue application, crop rotation and soil fertility amendments (low fertiliser, high fertiliser, manure, manure + low fertiliser and manure + 60 kg N ha−1) treatments. Reduced tillage increased beetle abundance by 4.6% relative to soil inversion tillage. Crop residue application increased the abundances of Platynus assimilis, Zophosis boei and total beetles by two to three times. Meanwhile, Renatiella reticulata increased by 628.6% in high fertiliser compared to manure + 60 kg N ha−1, manure + low fertiliser and the control. In crop rotation + crop residue retention plots, application of sole manure at 10 t ha−1 increased the Shannon index by 360–365% relative to manure + 60 kg N ha−1 and manure + low fertiliser. Based on the findings in this study, it can be concluded that reduced tillage, retention of crop residues on the soil surface and application of manure increase surface-dwelling beetle abundance and diversity.

Cropping system partially offsets tillage-related degradation of soil organic carbon and aggregate properties in a 30-yr rainfed agroecosystem

Soil tillage increases the susceptibility of agricultural soils to erosion and organic carbon losses, but tillage effects could be mitigated through other management practices such as crop rotation. Here, we evaluated the 30-year impacts of tillage intensity and cropping system on surface soil bulk density, nutrient availability, dry aggregate size distribution, and water-stable aggregation. This study was established in 1980 in eastern Nebraska USA, and included six tillage treatments of varying intensity (no-till, ridge till, disk till, subsoil rip, chisel plow, moldboard plow) and four crop rotation treatments (continuous soybean [Glycine max (L.) Merr.]; soybean-corn [Zea mays L.]; corn-soybean, continuous corn) in a randomized block design with six replicates. Surface soils were sampled in 2011 and soil aggregate properties assessed, including occluded particulate organic matter (oPOM) in micro/macroaggregates (0.053–0.5 mm) and mega-aggregates (>2.0 mm). Because of significant treatment differences in bulk density, soil properties were converted to an equivalent soil mass (ESM) basis to more accurately assess management effects. After 30 years, only the main effects of tillage and crop rotation were significant for most measured soil properties. Surface soil organic carbon (SOC) stocks (ESM for ∼0−30 cm soil depth) decreased with tillage intensity, and stocks were higher when corn was included in the cropping system. Dry aggregate size distributions shifted towards smaller size classes as tillage intensity increased and whenever corn was included in the cropping system. As a result, aggregate mean weight diameter (mm) followed a similar trend. Soil stocks of water-stable mega-aggregates also decreased with increasing tillage intensity. In near-surface soils (0–7.5 cm), highly-erodible aggregate oPOM was highest in no-till soils and was more sensitive to tillage disturbance (56–69% loss) than mega-aggregate oPOM (5–35% loss). Even in no-till soils, highly-erodible aggregate oPOM concentrations decreased under continuous corn compared to rotated systems likely due to greater frequency of fertility management-related soil disturbances (i.e. fertilizer injection annually vs every two years). These results suggest that cropping systems that maximize plant carbon inputs can partially mitigate soil erosion risks due to long-term tillage, but that other crop management-related soil disturbances (i.e. method of fertilizer application) could limit the mitigating effect of cropping system.

Corn-soybean rotation, tillage, and foliar fungicides: Impacts on yield and soil fungi

• Rotating crops is key to achieving high soybean and corn yield. • Prophylactic foliar fungicides resulted in a small increase in soybean seed yield. • Continuous corn and soybean have distinct bulk soil fungal communities. • Foliar fungicide treatments did not have an impact on bulk soil fungal communities. Fungal diseases can have a detrimental impact on soybean and corn yield. Foliar fungicides are used to manage fungal diseases and minimize yield loss, along with cultural practices like tillage and crop rotation. Prophylactic foliar fungicide use does not consistently increase yield for corn and soybean, especially when disease pressures are low. Also, there are concerns about the impact of fungicides on non-target organisms, including fungi living in the soil. We tested the effects of tillage, crop rotation, and foliar fungicide use on corn grain and soybean seed yield over three growing seasons. For both crops, rotation was key to achieving high yields, although there was an interaction of tillage × crop rotation for soybean and crop rotation × fungicide for corn. For soybean seed yield, both foliar fungicide treatments showed a small yield increase over untreated plots. Additionally, we assessed bulk soil fungal communities in a subset of treatments (crop rotation and fungicide treatments in no-till plots), using ITS sequencing and PLFA-FAME. We observed distinct fungal communities in the continuously cropped treatments, while annually rotated communities were very similar. There was also greater overall microbial biomass and a higher relative abundance of arbuscular mycorrhizae fungi associated with continuous corn. There were no differences in soil fungal communities or microbial biomass associated with foliar fungicide treatments. Based on our findings, we recommend that farmers use integrated pest management strategies to manage fungal diseases, which may include fungicide applications, if they are justified by economic disease thresholds or prediction tools.

Conservation Agriculture Practices Can Improve Earthworm Species Richness and Abundance in the Semi-Arid Climate of Eastern Cape, South Africa

Earthworms play a pivotal role in the regulation of soil health. Studies that explore the effects of conservation agriculture (CA) principles on earthworms under the semi-arid climate of the central Eastern Cape (EC) of South Africa (SA) are limited. Therefore, this study investigated the effects of tillage, crop rotations, and residue management on earthworms’ abundance and species richness. The study design followed a split-split plot with three replicates. The main plot was allocated to tillage treatment, which had conventional tillage (CT) and no-tillage (no-till) as factors. Crop rotation treatment was allocated to a subplot, and had maize (Zea mays)–fallow–maize (MFM), maize–fallow–soybean (Glycine max) (MFS), maize–wheat (Triticum aestivum)–maize (MWM), and maize–wheat–soybean (MWS). Residue management was in the sub-subplot with residue retention and residue removal. The study was carried out over four cropping seasons: summer 2015–2016, winter 2016, spring 2016, and summer 2016–2017. The results showed that the genera Amynthas and Lumbricus, both belonging to the anecic group, and Dendrobaena, belonging to the epigeic group, were present. Earthworm species diversity and density were highest under no-till than under CT. Residue retention improved earthworm density regardless of tillage management. Rotations that had fallow periods recorded lower earthworm numbers as compared to continuous cropping systems where wheat was grown in winter. The study concluded that maize–wheat–soybean (MWS) rotation with residue retention results in the highest earthworm abundance and species richness.