Energy balance and efficiency in crop rotation systems

The production system model that has been adopted in most Brazilian regions, the soybean/second corn crop succession, has led to problems in water and soil conservation and favorable conditions for diseases, pests, and weeds in the agricultural system and, consequently, increasing its energy use. Crop rotation is an alternative to this production model, directly interfering with the problematic aspects of the crop succession system and, consequently, its energy balance. Therefore, this study aimed to identify the crop rotation system with the best energy balance and efficiency. The data on the quantity of inputs (seeds, fertilizers, pesticides, and fuel), labor, and grain yield used in the study were collected from a crop rotation experiment conducted at the experimental station of the Rural Development Institute of Paraná - IAPAR-EMATER, Londrina, PR, Brazil, from 2014 to 2020. The experimental design consisted of randomized blocks, with six treatments and four replications. The treatments consisted of T1 (second corn crop/soybean), T2 (white oat/soybean, triticale/corn, and wheat/soybean), T3 (rye + black oat/soybean, black oat + fodder radish/corn, and congo grass/soybean), T4 (canola/corn, crambe/corn; canola/soybean); T5 (buckwheat-fodder radish/corn, bean/soybean, and buckwheat-white oat/ soybean), and T6 (wheat/corn, canola/corn + congo grass, and bean/soybean). The different crop rotations and the traditional second corn crop/soybean system provided positive energy balance and efficiency, that is, they produced more energy than they consumed. The canola/corn, crambe/corn, and canola/soybean rotation systems had the highest energy balance and efficiency, with values of 866,442.27 MJ ha−1 and 10.27, respectively, mainly due to corn cultivation in the summer, which resulted in a higher energy return than the other grain-producing crops.

Improving Farmers’ Revenue in Crop Rotation Systems with Plot Adjacency Constraints in Organic Farms with Nutrient Amendments

The search for sustainable agriculture is leading many economies to turn to crop rotation systems and to abandon monoculture systems which generally require increased use of pesticides and synthetic fertilizers. But the optimization of crop rotation remains a challenge, especially when considering organic farming. This work tackles the optimization of crop rotation in traditional organic farms with plot adjacency constraints and nutrient amendments. In the present configuration, each farmer owns a certain quantity of rudimentary equipment and a number of workers, all considered as resources. Farms are subdivided into plots and each plot allows only one crop at a given period. At a given interval of time, each plot receives a certain quantity of nutrient. The generated rotations are of fixed durations for all plots and the objective is to maximize farmers’ income. A linear programming approach is used to determine the solution of the proposed farming model. Three levels of constraints are combined in the linear program to generate realistic rotations: (i) biophysical constraints including crop succession and plot adjacency; (ii) structural constraints including budget and resources; (iii) organizational constraints such as nutrient amendment and market demand. To evaluate the performance of the model, scenarios based on real-world data has been defined and solved using free solvers. The solutions obtained indicate that all the constrains are satisfied. In addition, farmers’ revenue is improved, reaching a stationary position when the quantity of available resources is equal or greater than the quantity of required resources. Finally, Cbc solver is faster than GLPK solver; and it provides solutions on larger instances where GLPK does not.

Crop succession and split-application of nitrogen effects on common bean yield in short no-tillage system

Evaluating the effects of crop successions in no-tillage system (NTS) is essential for the correct recommendation of agronomic practices, such as top-dressing nitrogen fertilization. The aim was to evaluate the effect of the crop succession and the splitting of top-dressing N fertilization on the agronomic performance and economic viability of common bean crop. The experiment was conducted in southeastern Brazil for two agricultural seasons in an area under NTS, using a split-plot in randomized complete block design. The plots represented three cropping successions (maize in sole crop, maize intercropped with Urochloa ruziziensis and U. ruziziensis in sole crop) and the subplots composed of ten combinations of splitting of top-dressing N, at the stages V3, V4 and R5 of the common bean crop. In relation to the single application of the N dose of 90 kg ha−1, the common bean had higher response as a function of the N splitting schemes adopted, regardless of the previous cropping succession. The cropping successions evaluated did not interfere with the seed yield of common bean as subsequent crop, even at the beginning of the establishment of NTS. To obtain higher seed yield and economic viability, the N dose of 90 kg ha−1 indicated for the crop must be split and applied among the phenological stages V3, V4 and R5.

Impacts of the Winter Pea Crop (Instead of Rapeseed) on Soil Microbial Communities, Nitrogen Balance and Wheat Yield

Due to legume-based systems improving several aspects of soil fertility, the diversification of agrosystems using legumes in crop succession is gaining increasing interest. The benefits of legumes aroused the interest of farmers in the association of the Economic and Environmental Interest Group (EEIG), who introduced the idea of using the winter pea instead of rapeseed in their crop succession. The aim of this study is to evaluate the effects of the winter pea compared to those of rapeseed, as a head crop of the rotation, on soil microbial communities, enzyme activities, nitrogen (N) balance and yields. The field experiment involved two farmer plots that were selected within the EEIG. In each plot, two crop successions, including winter pea–wheat and rapeseed–wheat with fertilized and unfertilized strips, were examined for two years. Three times a year, under the wheat crop, composite soil samples were collected at depths of 0–20 cm, for microbial abundance and enzyme activity analyses, and twice a year at a depth of 0–60 cm, for the measuring of the mineral N. The results showed that the rapeseed–wheat succession maintained or enhanced soil bacterial and fungal biomasses and their enzyme activities. The winter pea–wheat succession enriched the soil’s mineral N content more consistently than the rapeseed–wheat succession. The mineral N enhancement’s effect was maintained under the wheat crop. Overall, the impact of the winter pea was positive on the soil’s N dynamics, but wheat yields were equivalent regardless of the previous crop (winter pea or rapeseed with and without fertilization). In the Normandy region, as rapeseed requires a large amount of N fertilizer and pesticide to maintain the yield and quality of crop products, it is suitable to favor the introduction of the winter pea as the head crop of the rotation, which indirectly allows for a reduction in the costs of input production and use, the working time of farmers and environmental pollution.

Soil physical quality in response to intensification of grain production systems

ABSTRACT The Brazilian Cerrado stands out in relation to grain production, however, in this region the occurrence of summer and irregular rainfall, drastically harm the non-irrigated production. Conservationist managements favor the soil physical quality and, consequently, the efficiency of soil water consumption. The objective of this study was to evaluate the soil physical quality, as a function of the conservation managements adopted, by using physical soil quality indicators, and to verify its relation with the soil organic carbon stocks and the grain yield in the Cerrado of Minas Gerais state, Brazil. For that, six treatments were evaluated: soybean (1) and maize (2) monocultures crop systems at medium level of investment in soil fertilization, soybean-maize crop succession at medium (3) and high (6) level of investment in soil fertilization, and crop succession of soybean-maize and intercropped with Urochloa ruziziensis at medium (4) and high (5) level of investment in soil fertilization, during the initial stage of no-tillage system. The treatments 3, 4, 5 and 6 showed improvement in the soil physical quality in relation to the monoculture. Pore distribution and soil organic carbon content were the main responsible for discriminating the intensified crop systems. Attributes related to water availability were important for plant growth in the 0-0.05 m layer, while for the 0.15-0.20 m layer, the highest soil aeration stood out. Productivity did not correlate with the evaluated attributes.

Microbial biodiversity as related to crop succession and potato intercropping for management of brown rot disease

Potato brown rot, caused by Ralstonia solanacearum, ranked globally as the second most important bacterial plant pathogen. In the present study, the influence of different cropping programs in potato brown rot management was investigated in four infected fields in Egypt. Two districts were selected as sandy soils in Giza (Wardan) and Behera (Ganuob El-Tahrir) governorates. The other two were selected as silty clay in Minufyia (Talia) and Beni-Suef (Sids) governorates. The followed crop succession included corn, potato intercropped with cabbage, onion, cowpea, wheat, corn again, and ended by potato. The pathogen was undetectable after corn, onion, and wheat. It decreased in cowpea and cabbage rhizospheres in the clay soils. The pathogen was undetectable at all districts, except at Sids, where the pathogen was significantly decreased but was not eradicated. This was possibly attributed to the high ratio of NO3− and Na+ at this district. Decreased R. solanacearum density after corn coincided with the high ratio of fluorescent pseudomonads, endospores, and actinomycetes, being most clear in the poor soils (Wardan) and less clear under iron excess at Ganoub El-Tahrir as well as the clay soils. Corn rhizosphere supported an array of antagonistic actinomycetes such as strains similar to Streptomyces intermedius, Streptomyces albidoflavus group, Streptomyces argenteolus group, and Streptomyces erythrogriseus. Intercropping potato with cabbage decreased the density of the pathogen in rhizosphere, which is associated with greater antagonistic fluorescent pseudomonads, Bacillus spp. and Serratia spp. Onion soil and rhizosphere associated with abundance of antagonists and fluorescent pseudomonads, followed by S. maltophilia and Bacillus spp. Wheat soil and rhizosphere supported fluorescent pseudomonads and antagonistic Streptomyces spp., especially in sandy soils. The pathogen was undetectable after planting the ending potato in the three districts, Wardan, Ganoub El-Tahrir, and Talia. This was accompanied by a general oligotrophism and increased ratio of fluorescent pseudomonads, endospores bacteria, and actinomycetes along with a diversity of R. solanacearum antagonists such as S. maltophilia, Citrobacter freundii, Acinetobacter sp., Delftia sp., and Serratia marcescens.