Lifetime productivity of dairy cows in smallholder farming systems of the Central highlands of Kenya

Evaluation of lifetime productivity is sensible to target interventions for improving productivity of smallholder dairy systems in the highlands of East Africa, because cows are normally not disposed of based on productive reasons. Feeding strategies and involuntary culling may have long-term effects on productive (and therefore economic) performance of dairy systems. Because of the temporal scale needed to evaluate lifetime productivity, experimentation with feedstuffs in single lactations is not enough to assess improvements in productivity. A dynamic modelling approach was used to explore the effect of feeding strategies on the lifetime productivity of dairy cattle. We used LIVSIM (LIVestock SIMulator), an individual-based, dynamic model in which performance depends on genetic potential of the breed and feeding. We tested the model for the highlands of Central Kenya, and simulated individual animals throughout their lifetime using scenarios with different diets based on common feedstuffs used in these systems (Napier grass, maize stover and dairy concentrates), with and without imposing random mortality on different age classes. The simulations showed that it is possible to maximise lifetime productivity by supplementing concentrates to meet the nutrient requirements of cattle during lactation, and during early development to reduce age at first calving and extend productive life. Avoiding undernutrition during the dry period by supplementing the diet with 0.5 kg of concentrates per day helped to increase productivity and productive life, but in practice farmers may not perceive the immediate economic benefits because the results of this practice are manifested through a cumulative, long-term effect. Survival analyses indicated that unsupplemented diets prolong calving intervals and therefore, reduce lifetime productivity. The simulations with imposed random mortality showed a reduction of 43% to 65% in all productivity indicators. Milk production may be increased on average by 1400 kg per lactation by supplementing the diet with 5 kg of concentrates during early lactation and 1 kg during late lactation, although the optimal supplementation may change according to milk and concentrate prices. Reducing involuntary culling must be included as a key goal when designing interventions to improve productivity and sustainability of smallholder dairy systems, because increasing lifetime productivity may have a larger impact on smallholders’ income than interventions targeted to only improving daily milk yields through feeding strategies.     

Diversity of coevolved weeds in smallholder maize fields of Mexico and Zimbabwe

Theory and empirical data suggest the areas of origin of a crop to be the general area of origin of its coevolved weeds. These longer evolved weeds would have an advantage over species with a shorter evolutionary time and migrate more successfully. We seek to identify patterns by comparing two regions with a shared crop, similar physiographic traits, but little direct contact, one of which is the area of origin of the crop. We compared the diversity of the maize weed flora and its edible components between two rural villages each of Oaxaca, Mexico, and Honde Valley, Zimbabwe, using vegetation sampling, interviews and participatory observation. The Mexican fields had higher species richness and diversity than the Zimbabwean ones. Species richness and densities were higher in the villages that receive more rainfall. Mexican fields had a mainly native weed flora with almost 80% American species and very few of African origin, whereas Zimbabwe had 32% of American and 50% of African origin. The regions shared seven American species and one of African origin. American/Mesoamerican agrestal weeds appear to be more successful in maize. Subsistence farmers in both study areas consumed about 19 edible weed species of which four were common to all villages. Our results also suggest that the presence of 3–4 species of edible weeds per field may be a general pattern in the maize-based systems, and that people not necessarily want or need more, so usefulness—at least as an edible plant—would have a limited influence on migration success.     

水肥耦合对玉米籽粒全氮含量的影响

采用四因素五水平(1/2实施)二次通用旋转组合设计,选取灌水、施氮肥、施磷肥和秸秆覆盖四因素作为试验因素,在辽西半干旱区褐土农田进行了水肥耦合效应长期定位试验。按照二次通用旋转组合设计统计分析方法建立回归模型,分析了水肥耦合对玉米籽粒全氮含量的影响。结果表明:水肥单因子对籽粒全氮的含量有较明显的影响,影响顺序为施氮秸秆覆盖施磷灌水;当灌水量为700m3.hm-2、施氮量为180kg.hm-2、施磷量为120kg.hm-2和秸秆覆盖量为7500kg.hm-2时,它们每个因素对玉米籽粒全氮含量的影响都集中11.7g·kg-1,此时籽粒蛋白质含量为73g·kg-1,产量为12000kg.hm-2,表明该处理组合下,玉米的经济效益和生态效益达到最佳,推荐生产上以此进行施肥。     

Small ruminant production in smallholder and pastoral/extensive farming systems in Kenya

A survey was conducted by way of personal interviews with 562 respondents comprising 459 farmers and 103 butchers/traders in selected districts in the central and western parts of Kenya, consisting of three predominantly smallholder and four predominantly pastoral/extensive districts. The study aimed to provide a better understanding of smallholder and pastoral/extensive sheep and goat farming systems in the tropics, by taking Kenya as an example. The results showed that 58% of the pastoral/extensive farmers and 46% of the smallholders indicated livestock as their main activity. Small ruminants ranked closely behind cattle in their importance. Thirty-four percent of the households kept only sheep, 18% only goats and 48% both species. The survey demonstrated the relative importance to the farmers of tangible benefits of farming sheep and goats (e.g., regular cash income, meat, manure and, in the case of goats, milk) versus intangible benefits (e.g., the role of small ruminants as an insurance against emergencies). Regular cash income and an insurance against emergencies were the highest priorities. Seventy-eight percent of the farmers reported animal sales over the previous 12 months of the survey date. Of these sales, the income was spent on school fees (32%), purchase of food (22%), farm investment (18%), medical expenses (10%), off-farm investment (9%), social activities (5%) and re-stocking (4%). Indigenous genotypes were predominant among the pastoralists and mixed crosses predominant among the smallholders. A range of traits: growth rate, body size, body shape, drought tolerance, meat quality, fertility, disease and heat tolerance, prolificacy and temperament were all considered important for both sheep and goats in both farming systems and across the different genotypes. Compared with other pure breeds, the Red Maasai sheep and the Small East African goats were rated poorly in terms of body size, body shape, growth and fertility, but highly in terms of drought and (for the Red Maasai) heat tolerance by both smallholder and pastoralist farmers. In general, crosses were perceived less favourably than indigenous pure breeds. Body size and performance ranked as the most important traits in the choice of breeding males. Approximately half the farmers inherited their males, reared them on the farm and kept them for an average of 2–3 years. Uncontrolled mating within the household's flock was predominant in both farming systems. Over 98% of the farmers reported incidence of disease, especially pneumonia (in pastoral/extensive areas), helminthosis, tick-borne diseases, diarrhoea and foot-rot. Over 95% of the farmers fed supplements in both dry and wet seasons. Pure exotic and indigenous × exotic genotypes fetched higher prices than indigenous genotypes due to their heavier body weight. In conclusion, the foregoing issues need attention in genetic improvement programmes, with more emphasis on the conservation and utilisation of indigenous small ruminant genotypes.     

Plant nutrient management for enhanced productivity in intensive grain production systems of the United States and Asia

Plant and Soil - Are present nutrient management recommendations for the world's major cereal cropping systems adequate to sustain the productivity gains required to meet food demand while also...     

High-density linkage mapping of vitamin E content in maize grain

Vitamin E refers to eight distinct compounds collectively known as tocochromanols and can be further divided into two classes, tocotrienols and tocopherols. Tocochromanols are the major lipid-soluble antioxidants in maize (Zea mays L.) grain. Enhancing vitamin E content of maize through plant breeding has important implications for human and animal nutrition. Four inbred lines exhibiting unique variation for tocochromanol compounds were chosen from the Goodman maize diversity panel to construct two biparental mapping populations (N6xNC296 and E2558xCo125). The N6xNC296 population was developed to analyze segregation for α-tocopherol and α-tocotrienol content. The E2558WxCo125 population was developed to analyze segregation for the ratio of total tocotrienols to tocopherols. The tocochromanol variation in two replicates of each population was quantified using liquid chromatography-diode array detection. Using high-density linkage mapping, novel quantitative trait loci (QTL) in the N6xNC296 population were mapped using tocopherol ratio traits. These QTL contain the candidate gene homogentisate phytyltransferase (ZmVTE2) within the respective support intervals. This locus was not mapped in a previous genome-wide association study that analyzed tocochromanols in the Goodman diversity panel. Transgressive segregation was observed for γ- and α-tocochromanols in these populations, which facilitated QTL identification. These QTL and transgressive segregant families can be used in selection programs for vitamin E enhancement in maize. This work illustrates the complementary nature of biparental mapping populations and genome-wide association studies to further characterize genetic variation of tocochromanol content in maize grain.     

The relationship of proline content and metabolism on the productivity of maize plants

The free proline content in maize ear-leaves, silk and pollen were analyzed in field grown plants which had matured to the pollination stage. Using maize hybrids PR34F02, PR35P12 and PR36B08 field trials were set up at two locations in eastern Croatia in two different years. Two enzymes of proline metabolism were analyzed in the same leaf samples and specific activities of synthetase (P5CS) and proline dehydrogenase (PDH). Plant productivity was evaluated at harvest by the estimation of total and fully developed grain number per ear and per plant, the mean single grain mass, and the mass of grain per plant. The year in which the plants were grown had a very significant effect on the free proline content in the leaf and pollen, as well as on the enzyme activities assayed. The differences between the plants from the two localities were very significant in all tested parameters of plant grain productivity. There was a significant genotype effect on proline content and P5CS total activity in leaf and on all the productivity parameters. Some of the correlations established suggest that the rate of proline synthesis and degradation in maize ear-leaf at pollination might contribute to the final grain production of the maize plant. Multiple regression analyses was used to further analyze the relationship between proline and grain productivity, but it is clear that future work should include other environmental conditions, plant species and organs such as roots.Key words: maize, maize silk, plant productivity, pollen, proline, proline dehydrogenase, Δ¹-pyrroline-5-carboxylate synthetase, Zea mays L.     

Effects of tillage intensity on nitrogen dynamics and productivity in legume-based grain systems

In 1988 an experiment was established at the Rodale Institute Experimental Farm to study weed control and nitrogen (N) management in rotations with grain crops and N-fixing green manures under reduced tillage without the use of herbicides. Tillage intensities ranging from moldboard plow (MP) to continuous no-till (NT) were compared. We present results for maize production in 1994, the seventh year of the experiment. Our goal was to further investigate reduced tillage regimes that alternated no-till with different forms of primary tillage in legume-based systems. In the chisel-disc (CD) and MP treatments comparable yields were achieved under so-called organic (weeds controlled with cultivation and green manure N source) and conventional management (weeds controlled with herbicides and mineral N fertilizer applied). Weed competition in these treatments was minimal and the N status of maize plants was essentially the same regardless of the N source (fertilizer or green manure). Of the four organic no-till maize treatments, only the mixed-tillage system with cultivation for weed control (CD-NTc) produced yields comparable to conventional NT maize. The fate of vetch N as well as temporal N dynamics were largely determined by tillage intensity and the handling of the vetch residues at maize planting. Treatments with primary tillage (CD and MP) had extremely high levels of mineral N early in the season and had greater average net N-mineralization, even though N content of hairy vetch in these treatments was equal to or lower than that in treatments with mow-killed vetch. In terms of soil mineral N concentrations, the CD-NTc treatment was similar to the other mow-killed vetch/no-till maize treatments. However, N availability in this treatment was greater, probably due to more complete decomposition of green manure residues. Cultivation for weeds not only helped control weeds but also increased mineralization of the vetch residues, which in turn increased the N supply during the period of maximum N demand by the maize. Carefully designed rotations combining tillage reductions with the use of leguminous N sources can have multiple benefits, including improved timing of N availability, reduced herbicide applications, and improved soil quality in the long term. This revised version was published online in June 2006 with corrections to the Cover Date.     

The effect of enhanced carotenoid content of transgenic maize grain on fungal colonization and mycotoxin content

Novel strategies that address vitamin A deficiency have been developed, such as high-carotenoid maize, a biofortified transgenic maize line rich in carotenoids generated by genetic transformation. The South African white maize inbred (M37W), which is devoid of carotenoids, was engineered to accumulate high levels of β-carotene (provitamin A), lutein, and zeaxanthin. Maize seeds contaminated with fumonisins and other mycotoxins pose a serious threat to both humans and livestock. During three consecutive harvests, the fungal incidence and the fumonisin and aflatoxin content of maize seeds grown in an experimental field in Catalonia (Northeastern Spain) were evaluated. Fungal infection was similar in high-carotenoid maize and its isogenic line, with Fusarium verticillioides being the most prevalent fungus in all the harvests. Neither Aspergillus spp. nor aflatoxin contamination was found. Fumonisin levels were lower in high carotenoid than in its isogenic line, but this reduction was statistically significant in only 2 of the 3 years of study. Our results suggest that high carotenoid content reduces fumonisin levels in maize grains.     

Effect of absence of developing grain on carbohydrate content and senescence of maize leaves

In maize (Zea mays L.) grown under normal conditions in Rhodesia, prevention of pollination or removal of the ears after flowering caused premature senescence of the leaves above the ear, preceded by the appearance of a purplish red color. In plants from which the ears had been removed the concentration of sugars and starch increased markedly in both upper and lower leaves, the increase being greater in the upper leaves.     

Soil resource heterogeneity in the form of aggregated litter alters maize productivity

Conservation agriculture in its version of permanent raised bed planting with crop residue retention increases yields and improves soil characteristics, e.g. aggregate distribution, organic matter content, so it remained to be seen how greenhouse gas emissions and dynamics of C and N might be altered. The objective of this study was to investigate how conservation agriculture with permanent raised beds, tied ridges, i.e. dykes within the furrows to prevent water run-off, and residue retention affected greenhouse gas emissions. A field experiment was started in 1999 comparing permanent and conventionally tilled raised beds with different residue management under rain fed conditions. Soil was characterized and emissions of CH₄, N₂O and CO₂ and dynamics of NH₄ ⁺, NO₂ ^? and NO₃ ^? were monitored in a laboratory experiment. The crop and tied ridges had no effect on soil characteristics and dynamics of C and N. Tilled beds reduced the water holding capacity (WHC) 1.1 times and increased conductivity 1.3 times compared to soil under nontilled beds with retention of all crop residues. The WHC, organic C, soil microbial biomass and total N were ≥1.1 larger in soil from nontilled beds where the crop residue was retained compared to where it was removed after only 6 years. The emission of CO₂ was 1.2 times and production of NO₃ ^? 1.8 times larger in nontilled beds where the crop residue was retained compared to where it was removed. The CO₂ emission was 1.2 times and the emission of N₂O after 1 day 2.3 times larger in soil under tilled beds compared to nontilled beds with full residue retention, while the increase in concentration of NO₃ ^? was 0.05 mg N kg^?1 soil in the former and 2.38 in the latter. We found that permanent raised bed planting with crop residue retention decreased emissions of N₂O and CO₂ compared to soil under conventionally tilled raised beds. Production of NO₃ ^? is larger in soil with permanent raised bed planting with crop residue retention compared to conventionally tilled raised beds.     

The role of maize root size in phosphorus uptake and productivity of maize/faba bean and maize/wheat intercropping systems

Interspecific root/rhizosphere interactions affect phosphorus (P) uptake and the productivity of maize/faba bean and maize/wheat intercropping systems. The aim of these experiments was to determine whether manipulation of maize root growth could improve the productivity of the two intercropping systems. Two near isogenic maize hybrids (the larger-rooted T149 and smaller-rooted T222) were intercropped with faba bean and wheat, under conditions of high- and low-P availability. The larger-rooted T149 showed greater competitive ability than the smaller-rooted T222 in both maize/faba bean and maize/wheat intercropping systems. The higher competitive ability of T149 improved the productivity of the maize/faba bean intercropping system in P-sufficient conditions. In maize/wheat intercropping systems, root growth, shoot biomass, and P uptake of maize were inhibited by wheat, regardless of the P-supply. Compared with T222, the larger-rooted T149 suffered less in the intercropping systems. The total biomass of the maize/wheat intercropping system was higher for wheat/T149 than for wheat/T222 under low-P conditions. These data suggested that genetic improvement of maize root size could enhance maize growth and its ability to compete for P resources in maize/faba bean and maize/wheat intercropping systems. In addition, depending on the P availability, larger maize roots could increase the productivity of intercropping systems.     

Crop rotation and residue management effects on carbon sequestration,nitrogen cycling and productivity of irrigated rice systems

The effects of soil aeration, N fertilizer, and crop residue management on crop performance, soil N supply, organic carbon (C) and nitrogen (N) content were evaluated in two annual double-crop systems for a 2-year period (1994–1995). In the maize-rice (M-R) rotation, maize (Zea mays, L.) was grown in aerated soil in the dry season (DS) followed by rice (Oriza sativa, L.) grown in flooded soil in the wet season (WS). In the continuous rice system (R-R), rice was grown in flooded soil in both the DS and WS. Subplot treatments within cropping-system main plots were N fertilizer rates, including a control without applied N. In the second year, sub-subplot treatments with early or late crop residue incorporation were initiated after the 1995 DS maize or rice crop. Soil N supply and plant N uptake of 1995 WS rice were sensitive to the timing of residue incorporation. Early residue corporation improved the congruence between soil N supply and crop demand although the size of this effect was influenced by the amount and quality of incorporated residue. Grain yields were 13-20% greater with early compared to late residue incorporation in R-R treatments without applied N or with moderate rates of applied N. Although substitution of maize for rice in the DS greatly reduced the amount of time soils remained submerged, the direct effects of crop rotation on plant growth and N uptake in the WS rice crops were small. However, replacement of DS rice by maize caused a reduction in soil C and N sequestration due to a 33–41% increase in the estimated amount of mineralized C and less N input from biological N fixation during the DS maize crop. As a result, there was 11–12% more C sequestration and 5–12% more N accumulation in soils continuously cropped with rice than in the M-R rotation with the greater amounts sequestered in N-fertilized treatments. These results document the capacity of continuous, irrigated rice systems to sequester C and N during relatively short time periods. This revised version was published online in June 2006 with corrections to the Cover Date.     

Dietary zinc effects on zinc, calcium, and magnesium content in bones of growing rats

The aim of the present study was to assess dietary zinc effects on femur weight and mineral content in growing rats. For this purpose, 70 weanling Sprague-Dawley rats were divided into four groups. Each group was subject to a diet containing 2 (BZ), 5 (DZ), 10 (MZ), and 30 (CZ) ppm zinc. The calcium and magnesium content in all diets was 5 g/kg and 507 mg/kg, respectively. The animals were kept on this regime for 28 d and then sacrificed and their femurs were removed for analysis using atomic absorption spectrophotometry. The weights of the BZ and DZ groups were significantly different from the MZ and CZ groups (38.5±10.5, 89.9±13.7, 118.6±13.6 and 134±19.9 g, p<0.01) respectively. There were no differences between the MZ and CZ groups. Femur weight also varied with dietary zinc, as it was significantly different among all groups (BZ, 265±49 mg; DZ, 380±40 mg; MZ, 452±54 mg; CZ, 735±66 mg; p<0.01). The femur zinc content varied with diets, following a different pattern than the above parameters. Femur zinc from the BZ group (51.5±5.4 ppm) was significantly different from the MZ and CZ groups (115.9±14.2 and 175.0±13.5 ppm, respectively), whereas the DZ group (62.5±11.3 ppm) did not differ from the other three groups. The femur content of calcium (BZ, 83.2±9.8 mg/g; DZ, 88.0±9.2 mg/g; MZ, 90.2±13.6 mg/g; CZ, 83.1±14.7 mg/g) and magnesium (BZ, 1.82±0.13 mg/g; DZ, 1.98±0.09 mg/g; MZ, 1.93±14 mg/g; CZ, 1.83±0.19 mg/g) were not significantly different among the groups, nor was the calcium-magnesium ratio. These results suggest that although dietary zinc deficiency retards growth and causes bone fragility, bone deposition of calcium and magnesium and its ratio are not affected.     

Soil management effects on entomopathogenic fungi during the transition to organic agriculture in a feed grain rotation

The growing demand for organic products creates opportunities for farmers. Information on the consequences of management practices can help farmers transition to organic and take advantage of these prospects. We examined the interaction between soil disturbance and initial cover crop on naturally occurring entomopathogenic fungi (EPF) during the 3-year transition to organic production in a feed grain rotation in central Pennsylvania. Our experiment included four systems comprised of a factorial combination of two levels of primary tillage (full vs. reduced) and two types of initial cover crop (timothy/clover vs. rye/vetch). The cropping sequence consisted of an initial cover crop, followed by soybean, and finally, maize. The entire experiment was replicated in time, with the initiation lagged by 1 year. We detected four species of EPF (Metarhizium anisopliae, Beauveria bassiana, Isaria fumosorosea, and Isaria farinosa) by bioassay of soil samples collected four times during each field season. The latter three species were detected infrequently; therefore, we focused statistical analysis on M. anisopliae. Detection of M. anisopliae varied across sampling date, year in crop sequence, and experimental start, with no consistent trend across the 3-year transition period. M. anisopliae was isolated more frequently in the systems initiated with timothy/clover cover crops and utilizing full tillage; however, we only observed a tillage effect in one temporal replicate. M. anisopliae detection was negatively associated with soil moisture, organic matter, and zinc, sulfur, and copper concentrations in the soil. This study helps to inform farmers about management effects on soil function, specifically conservation biological control.     

Soil management effects on entomopathogenic fungi during the transition to organic agriculture in a feed grain rotation

The growing demand for organic products creates opportunities for farmers. Information on the consequences of management practices can help farmers transition to organic and take advantage of these prospects. We examined the interaction between soil disturbance and initial cover crop on naturally occurring entomopathogenic fungi (EPF) during the 3-year transition to organic production in a feed grain rotation in central Pennsylvania. Our experiment included four systems comprised of a factorial combination of two levels of primary tillage (full vs. reduced) and two types of initial cover crop (timothy/clover vs. rye/vetch). The cropping sequence consisted of an initial cover crop, followed by soybean, and finally, maize. The entire experiment was replicated in time, with the initiation lagged by 1 year. We detected four species of EPF (Metarhizium anisopliae, Beauveria bassiana, Isaria fumosorosea, and Isaria farinosa) by bioassay of soil samples collected four times during each field season. The latter three species were detected infrequently; therefore, we focused statistical analysis on M. anisopliae. Detection of M. anisopliae varied across sampling date, year in crop sequence, and experimental start, with no consistent trend across the 3-year transition period. M. anisopliae was isolated more frequently in the systems initiated with timothy/clover cover crops and utilizing full tillage; however, we only observed a tillage effect in one temporal replicate. M. anisopliae detection was negatively associated with soil moisture, organic matter, and zinc, sulfur, and copper concentrations in the soil. This study helps to inform farmers about management effects on soil function, specifically conservation biological control.     

Woody legume fallow productivity,biological N2-fixation and residual benefits to two successive maize crops in Zimbabwe

Plant and Soil - Three woody legumes were planted as two-year `improved fallows' to evaluate their residual nitrogen (N) effects on two subsequent maize crops under minimum and conventional...     

土壤肥力和施氮量对小麦氮素吸收运转及籽粒产量和蛋白质含量的影响

在不同土壤肥力条件下,研究了施氮量对小麦氮素吸收、转化及籽粒产量和蛋白质含量的影响。结果表明,增施氮肥可以提高小麦各生育阶段的吸氮强度,尤以生育后期提高的幅度为大认为是增施氮肥提高小麦籽粒产量和蛋白质含量的基础,增施氮肥虽提高了小麦植株的吸氮强度。吸氮量增加,但开花后营养器官氮素向籽粒中的转移率降低,增施氮肥不仅促进了小麦植株对肥料氮的吸收,而且也促进了对土壤氮的吸收,并讨论了在高、低土壤肥力条件下氮肥合理运筹的问题。     

Constitutive expression of cell wall invertase genes increases grain yield and starch content in maize

Grain size, number and starch content are important determinants of grain yield and quality. One of the most important biological processes that determine these components is the carbon partitioning during the early grain filling, which requires the function of cell wall invertase. Here, we showed the constitutive expression of cell wall invertase–encoding gene from Arabidopsis, rice (Oryza sativa) or maize (Zea mays), driven by the cauliflower mosaic virus (CaMV) 35S promoter, all increased cell wall invertase activities in different tissues and organs, including leaves and developing seeds, and substantially improved grain yield up to 145.3% in transgenic maize plants as compared to the wild‐type plants, an effect that was reproduced in our 2‐year field trials at different locations. The dramatically increased grain yield is due to the enlarged ears with both enhanced grain size and grain number. Constitutive expression of the invertase‐encoding gene also increased total starch content up to 20% in the transgenic kernels. Our results suggest that cell wall invertase gene can be genetically engineered to improve both grain yield and grain quality in crop plants.     

Soil microarthropods respond differently to simulated drought in organic and conventional farming systems

In Central Europe, summer droughts are increasing in frequency which threatens production and biodiversity in agroecosystems. The potential of different farming systems to mitigate detrimental drought effects on soil animals is largely unknown. We investigated the effects of simulated drought on the abundance and community composition of soil microarthropods (Collembola and Oribatida and Meso‐, Pro‐, and Astigmata) in winter wheat fields under long‐term conventional and organic farming in the DOK trial, Switzerland. We simulated drought by excluding 65% of the ambient precipitation during the wheat‐growing season from March to June 2017. The abundance of Collembola and Oribatida declined more consistently in conventionally managed fields compared to organically managed fields under simulated drought. The abundance of Collembola as well as Meso‐, Pro‐ and Astigmata, but not the abundance of Oribatida, increased in deeper soil layers due to simulated drought, suggesting vertical migration as a drought avoidance strategy. The species composition of Oribatida communities, but not of Collembola communities, differed significantly between drought treatments and between farming systems. Soil carbon content was a major factor structuring Oribatida communities. Our results suggest that organic farming buffers negative effects of drought on soil microarthropods, presumably due to higher soil carbon content and associated higher soil moisture and improved soil structure. This potential of organic farming systems to mitigate consequences of future droughts on soil biodiversity is promising and needs further exploration across larger climatic and spatial scales and should be extended to other groups of soil biota.