Reply on RC1

Behaviour of S-metolachlor and its oxanilic and ethanesulfonic acids metabolites under fresh vs. partially decomposed cover crop mulches: A laboratory study

On-farm assessment of organic matter and tillage management on vegetable yield, soil, weeds, pests, and economics in California

Agroecosystem nitrogen (N) loss produces greenhouse gases, induces eutrophication, and is costly for farmers; therefore, conservation agricultural management practices aimed at reducing N loss are increasingly adopted. However, the ecosystem consequences of these practices have not been well-studied. We quantified N loss via leaching, NH3 volatilization, N2O emissions, and N retention in plant and soil pools of corn conservation agroecosystems in Kentucky, USA. Three systems were evaluated: (1) an unfertilized, organic system with cover crops hairy vetch (Vicia villosa), winter wheat (Triticum aestivum), or a mix of the two (bi-culture); (2) an organic system with a hairy vetch cover crop employing three fertilization schemes (0 N, organic N, or a fertilizer N-credit approach); and (3) a conventional system with a winter wheat cover crop and three fertilization schemes (0 N, urea N, or organic N). In the unfertilized organic system, cover crop species affected NO3-N leaching (vetch > bi-culture > wheat) and N2O-N emissions and yield during corn growth (vetch, bi-culture > wheat). Fertilization increased soil inorganic N, gaseous N loss, N leaching, and yield in the organic vetch and conventional wheat systems. Fertilizer scheme affected the magnitude of growing season N2O-N loss in the organic vetch system (organic N > fertilizer N-credit) and the timing of loss (organic N delayed N2O-N loss vs. urea) and NO3-N leaching (urea >> organic N) in the conventional wheat system, but had no effect on yield. Cover crop selection and N fertilization techniques can reduce N leaching and greenhouse gas emissions without sacrificing yield, thereby enhancing N conservation in both organic and conventional conservation agriculture systems.

Meta-analysis on atmospheric carbon capture in Spain through the use of conservation agriculture

<i>Background and Objective</i>: The plight of farmers are worsening by the impact of climate change. This is evident in all agro-ecological zones in Ghana. Warming and variability in rainfall pattern is causing floods and long dry spells of drought with resultant effects of reduced food crop and livestock production. Conservation Agricultural (CA) practices was therefore introduced to address the challeges of conventional tillage. CA has therefore been identified as a substitute to conventional agriculture for sustainable agricultural productivity. The objective of the study was to assess the rate of adoption of CA practices in the Bawku Municipality in the Upper East region of Ghana. <i>Methodology</i>: The study was conducted in the Bawku Municipal area of Ghana. The research design used for the study was the mixed methods. The purposive sampling technique was used to select the Bawku Municipality as the major area where agricultural conservation practices occurs in the Upper East region. The simple random sampling technique was used to select ten (10) communities in the Municipality, whilst the systematic random sampling was used to select forty (40) respondents from each community for the study. The target population for the study was maize farmers in the Bawku Municipality. In all, a total of 358 respondents were interviewed for the study. Data was taken on socio-cultural and socio-economic characteristics of respondents. Data analysis was done using the Statistical Package for Social Sciences (SPSS). Descriptive statistics, such as frequencies, percentages, and means were computed. Cross tabulations of variables were also computed and the chi-square tests used to establish relationships. <i>Results</i>: The study revealed that age, sex, level of education, religion, household size, government policy, access to credit, source of income, farm size, and access to extension services were found to have significantly influenced adoption of CA practices. The results of the study indicated that majority of farmers were aware and had knowledge about CA practices. “No-tillage with cover crops, minimum tillage with cover crops, and crop rotation with cover crops” were the main practices of conservation agriculture in the study area. The study further revealed that majority of the farmers indicated that the practices of conservation agriculture reduces soil erosion, increases soil fertility, increases soil organic matter and improves agricultural productivity. <i>Conclusion</i>: Majority of farmers adopted CA practices in full. It is recommended that the Ghanaian government should boost CA practices by instituting an annual national award scheme to award hardworking CA practioners in Ghana.

Abstract. Changes in soil surface microrelief with cumulative rainfall under different tillage systems and crop cover conditions were investigated in southern Brazil. Surface cover was none (fallow) or the crop succession maize followed by oats. Tillage treatments were: 1) conventional tillage on bare soil (BS), 2) conventional tillage (CT), 3) minimum tillage (MT) and 4) no tillage (NT) under maize and oats. Measurements were taken with a manual relief meter on small rectangular grids of 0.234 and 0.156 m2, throughout growing season of maize and oats, respectively. Each data set consisted of 200 point height readings, the size of the smallest cells being 3×5 cm during maize and 2×5 cm during oats growth periods. Random Roughness (RR), Limiting Difference (LD), Limiting Slope (LS) and two fractal parameters, fractal dimension (D) and crossover length (l) were estimated from the measured microtopographic data sets. Indices describing the vertical component of soil roughness such as RR, LD and l generally decreased with cumulative rain in the BS treatment, left fallow, and in the CT and MT treatments under maize and oats canopy. However, these indices were not substantially affected by cumulative rain in the NT treatment, whose surface was protected with previous crop residues. Roughness decay from initial values was larger in the BS treatment than in CT and MT treatments. Moreover, roughness decay generally tended to be faster under maize than under oats. The RR and LD indices decreased quadratically, while the l index decreased exponentially in the tilled, BS, CT and MT treatments. Crossover length was sensitive to differences in soil roughness conditions allowing a description of microrelief decay due to rainfall in the tilled treatments, although better correlations between cumulative rainfall and the most commonly used indices RR and LD were obtained. At the studied scale, parameters l and D have been found to be useful in interpreting the configuration properties of the soil surface microrelief.

Conservation agriculture (CA), which encompasses minimum soil disturbance, residue retention either through crop residue, or cover crops and crop diversification-based crop management practices can modify the status of pest dynamics and activities under the changing climatic scenarios. CA has been advocated extensively to optimize the use of available resources, maintain the environmental quality, enhance crop productivity, and reduce the climate change impacts. Information related to the impacts of long-term CA-production systems under rice-based cropping systems on pest status is lacking, particularly in middle Indo-Gangetic Plains (MIGP). Under CA, puddling is completely avoided, and rice is directly sown or transplanted to maintain better soil health. Different sets of experimentations including farmers practice, partial CA and full CA (CA) as treatments in rice-based cropping systems, were established from 2009, 2015 and 2016 to understand the long-term impacts of CA on pest dynamics. In this study, direct and indirect effects of tillage (zero, reduced and conventional tillage), residue retention and cropping sequences on abundance and damage by pests were investigated. After 4–5 years of experimentation, populations of oriental armyworm [Mythinma (Leucania) (Pseudaletia) separata (Wlk.)] in wheat, mealybug [Brevennia rehi (Lindinger)] and bandicoot rat [Bandicota bengalensis (Gray)] in rice were found to increase abnormally in CA-based production systems. Conventionally tilled plots had a significant negative effect while residue load in zero-tilled plots had a significant positive effect on larval population build-up of M. separata. Zero tillage had a higher infestation of mealybug (52–91% infested hills) that used grassy weeds (Echinochloa colona, Echinochloa crusgalli, Cynodon dactylon, Leptochloa chinensis and Panicum repense) as alternate hosts. Cropping sequences and no disturbance of soil and grassy weeds had higher live burrow counts (4.2 and 13.7 burrows as compared to 1.47 and 7.53 burrows per 62.5 m2 during 2019–2020 and 2020–2021, respectively) and damaged tillers (3.4%) in CA-based practices. Based on the present study, pest management strategies in CA need to be revisited with respect to tillage, residue retention on soil surface, grassy weeds in field and cropping sequences to deliver the full benefits of CA in MIGP to achieve the sustainable development goals under the climate change scenarios.

THREE tillage systems of cotton were studied to determine their effects on surface runoff and sediment yield during growing period of 1985 and 1986 in the Tennessee Valley region of northern Alabama. They include; reduced tillage without a cover crop (RT), reduced tillage with a winter wheat cover crop (RTC) and conventional tillage (CT). Sediment yield was in the order of CT > RT > RTC in 1985. Runoff was the lowest from the RTC system followed by the CT and RT systems. In 1986, runoff from the CT was the lowest, followed by the RTC and RT, while sediment yield was in the order of CT > RTC > RT. The growth stage of cotton and the cultivations of the CT system influenced the patterns of runoff and sediment yield. More than 85% of the measured sediment yield and 50 to 70% of the runoff occurred during the first 2 months after planting. Seed cotton yields for all tillage systems were above average in 1985, but the highest yield occurred with the RT system. However, a drought during the critical stage of growth in 1986 caused reduced yield with all systems and the lowest yield occurred with the RT system.

The recent interest in the adoption of minimum tillage for crop production in the humid tropics for better soil and water conservation has raised questions concerning crop yield and nutrient absorption. There is lack of information on the most suitable method of P application with minimum tillage as compared to conventional tillage with tropical soils. The present study was therefore undertaken to investigate the interaction between soil tillage and P application methods on (a) P movement in the soil profile, (b) maize root distribution, (c) P content, and (d) maize yield.The experiment was conducted on Egbeda soil series (Oxic Paleustalf) in southern Nigeria in 1974 and 1975 using a split‐plot design with four replications. Conventional and minimum tillage were the main plots, P rates and placement were the sub‐plots.Root density of maize was increased with P application. There was a tendency of higher root concentration in the upper 10 cm of the soil surface with minimum tillage. Movement of broadcast P in the soil profile was observed to be slow with minimum tillage. However, broadcast, band, and hill methods of P application was observed to be equally effective in supplying adequate P to the maize crop at P rates of 20 kg P/ha on the Egbeda soil. Therefore, no effect of P placement method on maize yield was observed with both minimum and conventional tillage methods. The lower maize yield with minimum tillage in 1974 was attributed to early N‐ stress. In 1975 with 160 kg N/ha, maize yield was equal with conventional and minimum tillage methods.

Minimum tillage is a soil conservation practice involving a reduction in soil disturbance and topsoil compaction, which could minimize environmental impact of the tobacco cultivation system. The objectives of this study were to evaluate the development and growth responses of Nicotiana tabacum and the changes in the physical and hydrological soil properties after the application of two different treatments: minimum tillage (MT) and conventional tillage (CT). MT did not cause any pronounced differences in the crop yield compared to CT, instead it positively affected the physical and hydrological soil properties and the plants’ vegetative growth. Under MT, the soil showed a higher structural stability than CT with significantly lower compaction values. With MT the soil showed a higher capacity to maintain and store water during the drought periods, evidenced by soil moisture values significantly higher than CT. Tobacco on MT showed a good response, significantly prolonging the vegetative growth stage which at harvest determined a higher stem height, greater number of leaves and longer internodes.

Temporal stability and patterns of runoff and runon with different cover crops in an olive orchard (SW Andalusia, Spain)

Worldwide, farmers are called upon to abandon harmful pesticides and adopt conservation agriculture for improving environmental sustainability, soil fertility, pest management and farm profits, among other benefits. Whereas the positive environmental benefits of conservation agriculture are non-questionable, pest management benefits are still a subject of debate. Abandonment of the plough and harmful pesticides towards conservation agriculture presented new challenges to farmers in terms of pest management. Pest problems are frequently reported as the main yield limiting factor for conservation agriculture in many production systems of the world, especially among the resource poor farmers. Here we first review the pest management benefits of conservation agriculture principles, with special focus on weeds and animal pests. In conservation agriculture, emphasis should be placed on use of different multiple and varied tactics incorporated into the cropping system design to avoid damaging levels of pests, thus minimizing the need for curative solutions. Conservation agriculture embraces integrated pest management, as it aims to incorporate reduced pesticide applications with cover crops, conservation tillage and crop rotation to strengthen natural pest control. We show that effective long term weed management in conservation agriculture systems is based on an integration of measures for limiting competitiveness of the weeds that are already in the field and growing with the crop, preventing the introduction of new weeds, and preventing the multiplication of the weeds that are already there. Although the abandonment of tillage towards no-till requires an initial investment on herbicides for weed control, herbicide requirement tends to decline over time with proper application of conservation agriculture. Proper selection of planting date, density and spatial arrangement of a crop can maximize the space it occupies early in the season and put competitive pressure on weeds. Crops can be rotated in sequences that are not only profitable, but highly effective at breaking animal pest cycles. Mixed cropping reduces pest populations by increasing environmental diversity and lowering the overall attractiveness of the environment. We then highlight some possible solutions to the major challenges for pest management through conservation agriculture practice. Promotion of integration of conservation agriculture principles with cultural measures is essential for pest management in conservation agriculture systems. In conservation agriculture, it is important for farmers to employ several strategies simultaneously so that if one strategy fails, then the other ones operate to prevent yield loss. The focus should not be just on how to fit various pest management tactics into the conservation agriculture production system, but also on how the system can be modified to accommodate various pest control tactics. We demonstrate that farmers practicing conservation agriculture have several cultural methods that they can put together to build up a good pest management strategy. Although cover crops and mulches are generally viewed as the first line of defense against weeds, the reduction in weeds is not enough to eliminate the need for chemical control. Cover crops can be used to reduce animal pest dispersal, colonization and reproduction on crops through maintenance of the cover crop as a sink for various pests, confusing the pests visually and by causing microclimate changes that reduce pest success. Fertilizer timing and placement strongly influences crop competition; and deep banding of fertilizer has the potential to enhance not only fertilizer use efficiency, but also crop resistance to animal pests and competitive ability against weeds. Proper selection of planting date, density and spatial arrangement of a crop can put competitive pressure on weeds and break animal pest cycles. Sanitation practices are important tools in conservation agriculture because of their ability to eliminate necessities that are important to the pests’ survival. The development of pest resistance will likely be minimal if host plant resistance is integrated with other control measures through conservation agriculture practice. A more holistic, integration approach of control tactics in conservation agriculture, which goes beyond the three principles, is essential for effective pest management.

Yield, soil Nitrogen content and weed control in six years of conservation agriculture on-farm field trials in Southwest Germany

SUMMARYThe present study compared slug, earthworm and carabid beetle abundance and slug damage to plants in minimum tillage (MT) and conventional tillage (CT) autumn-sown cereals. Winter barley was sown by CT and MT for 3 years followed by winter wheat for 6 years on a light-textured soil (Trial 1). Each cultivation was split so that straw was incorporated into the soil during cultivation in one split while the other did not receive straw. A similar investigation with winter wheat, over the same period, was undertaken on a nearby heavy-textured soil (Trial 2). The effects of method of cultivation and soil incorporation of straw on slug abundance and damage, and on earthworm populations were measured. Additionally, at Trial 1, the effects of cultivation and straw treatments on carabid beetle occurrence were measured in years 5–9. Over the 9 years, the method of cultivation had a significant effect on slug numbers in each trial. Slugs were more numerous in MT than CT plots, significantly so in 3 of the 9 years in Trial 1 and in 5 years in Trial 2. In Trial 1, slug numbers were significantly greater on no-straw than straw plots in 3 years as well as for the 9 years combined. Slug numbers did not differ between straw and no-straw plots in Trial 2. Slug numbers varied significantly between years and were influenced by factors other than the method of cultivation and straw application. Slug damage to seed and seedlings was quite low in each year (1–2%). Slug damage to cereal leaves at GS 23 was widespread in both trials, and severe in some years. MT had more leaf damage than CT in 5 of the 9 years in each trial, significantly so in 3 years in Trial 1 and in 4 years in Trial 2. Straw did not affect leaf damage in either MT or CT. Slug damage was not related to, nor did it affect either ear density or grain yield. The dominant slug species wasDeroceras reticulatum.Earthworm numbers were significantly greater in MT than CT, for combined years, in each trial. Annually, these differences were significant for 5 years in Trial 1 and 2 years in Trial 2. Straw plots had significantly more earthworms than no-straw, for combined years, in each trial. The latter differences were significant for 5 years in Trial 1 and 3 years in Trial 2. In MT, the positive effect of straw on earthworm numbers was significant in Trial 2 but not in Trial 1. In CT, the latter effect was significant in each trial.Lumbricusspecies were more numerous in MT than CT and in straw than no-straw treatments. The impact of cultivation on numbers of carabid beetles was species-specific. The large beetle,Pterostichus melanarius, was significantly more numerous in MT than CT in 2 of the 5 years and for the aggregate of 5 years. Small carabids (Bembidionspecies andTrechus quadristriatus) were significantly more abundant in CT than MT in 3 of the 5 years as well as for the aggregate of 5 years. Straw did not affect the number of any or all carabid species either for combined cultivations (MT + CT) or within either MT or CT. It is concluded that MT increases slug numbers, slug damage and earthworm numbers relative to CT cultivations. MT favours large carabid beetles and CT favours small beetles. Straw incorporation increases earthworm numbers but not slugs, slug damage or carabid beetles. Slug damage to cereal leaves does not affect ear density or grain yield in either MT or CT crops when sown to a depth of 40 mm and before 18 September.

Abstract. Interest in cover crops has been increasing in the Texas Rolling Plains (TRP) region, mainly to improve soil health. However, there are concerns that cover crops could potentially reduce soil water and thereby affect the yield of subsequent cash crops. Previous field studies from this region have demonstrated mixed results, with some showing a reduction in cash crop yield due to cover crops and others indicating no significant impact of cover crops on subsequent cotton fiber yield. The objectives of this study were to (1) evaluate the CROPGRO-Cotton and CERES-Wheat modules within the cropping system model (CSM) of the Decision Support System for Agrotechnology Transfer (DSSAT) for the TRP region, and (2) use the evaluated model to assess the long-term effects of growing winter wheat as a cover crop on water balances and seed cotton yield under irrigated and dryland conditions. The two DSSAT crop modules were calibrated using measured data on soil water and crop yield from four treatments: (1) irrigated cotton without a cover crop (CwoC-I), (2) irrigated cotton with winter wheat as a cover crop (CwC-I), (3) dryland cotton without a cover crop (CwoC-D), and (4) dryland cotton with a winter wheat cover crop (CwC-D) at the Texas A&amp;amp;M AgriLife Research Station at Chillicothe from 2011 to 2015. The average percent error (PE) between the CSM-CROPGRO-Cotton simulated and measured seed cotton yield was -10.1% and -1.0% during the calibration and evaluation periods, respectively, and the percent root mean square error (%RMSE) was 11.9% during calibration and 27.6% during evaluation. For simulation of aboveground biomass by the CSM-CERES-Wheat model, the PE and %RMSE were 8.9% and 9.1%, respectively, during calibration and -0.9% and 21.8%, respectively, during evaluation. Results from the long-term (2001-2015) simulations indicated that there was no substantial reduction in average seed cotton yield and soil water due to growing winter wheat as a cover crop. Keywords: CERES-Wheat, Cover crop, Crop simulation model, CROPGRO-Cotton, DSSAT, Seed cotton yield, Soil water.