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We study the role of social learning in the diffusion of cash crops in a resettled village economy in Brazil. We combine detailed geo-coded data on farming plots with dyadic data on social ties among settlers, and we leverage the variation in network formation induced by the landless workers' movement land occupation. By using longitudinal data on farming decisions over 15 years, we find evidence of significant peer effects in the decision to farm new cash fruits (pineapple and passion fruit). Our results suggest that social diffusion is heterogeneous along observed plot and crop characteristics, i.e. farmers growing water-sensitive crop are more likely to respond to the actions of peers with similar water access conditions. [ABSTRACT FROM AUTHOR]

The management practices impact on a crop succession system in newly implemented no-tillage area should be investigated to provide more accurate recommendations. A two-year experiment (2008/2009 and 2009/2010) was conducted in Southeastern Brazil to evaluate the interactions between crop succession (grasses/legume) and nitrogen splitting fertilization in common bean in a production system with newly implemented no-tillage. The experiment was conducted in a randomized block design, in a split-plot scheme. The cropping systems (plots) in spring/summer were: sole maize, maize intercropped with Urochloa ruziziensis and sole U. ruziziensis. The subplots consisted of ten splitting schemes of side-dressing nitrogen fertilization in common bean, with applications in the phenological stages V3 (first fully expanded trifoliate leaf), V4 (third fully expanded trifoliate leaf) and R5 (opening of floral buds). On average, stages V3, V4 and R5 occurred at 12, 22 and 38 days after emergence. The common bean grain yield (GY) was 5 to 12% lower when it was cultivated after sole U. ruziziensis compared to other successions. However, when U. ruziziensis was intercropped with maize, the GY of common bean was similar to that obtained in the succession with sole maize. Compared to the application in a single rate, the GY of common bean was on average 12% higher when nitrogen fertilization was split, and the best schemes were 45-00-45 and 45-45-00. On average, sole maize, maize intercropped with U. ruziziensis and sole U. ruziziensis promoted soil surface cover by crop residues left by the harvest of 79, 100 and 100%, respectively. Nitrogen fertilization in common bean did not affect the GY of maize in succession. Intercropping of maize with U. ruziziensis and nitrogen splitting fertilization (45-00-45 and 45-45-00) in common bean in succession allows obtaining the ecosystem benefits promoted by the forage without affecting the cash crops yield. [ABSTRACT FROM AUTHOR]

Increasing crop intensification while enhancing soil conservation is an important aspect of global food security. Intercropping (syn. interseeding) between cash crops and tropical forages improves soil cover, prevents soil erosion, and enhances land use via crop and livestock integration. In Brazil, intercropping between maize (Zea mays L.) and Brachiaria grass (Urochloa spp.) is the most commonly adopted system, with opportunities for expansion across tropical and subtropical landscapes worldwide. Nonetheless, there is little consensus on the effects of intercropping on the performance of each individual crop species. A meta-analysis was conducted to quantify the effect of intercropping on maize grain yield and Brachiaria grass biomass production and to understand the impact of environmental and management factors on intercropping performance. A literature search was conducted to retrieve peer-reviewed studies carried out on this intercropping system under field conditions. Manuscripts were scrutinized and included in this meta-analysis when they met the following criteria: i) data on maize grain yield and Brachiaria grass biomass under intercropping were reported, ii) inclusion of a control treatment (monocropping) for at least one species, and iii) field trials with at least three randomized replications. Our database included 429 data points extracted from 56 published manuscripts from all regions of Brazil. Relative to monocropping, intercropping reduced maize grain yield (−5.6 %) and Brachiaria grass biomass production (−64 %) in all scenarios. The intercropped maize grain yield was less affected under the following conditions: i) in the subtropical climate zone (−3.6 %), ii) sowing the intercrop early in the season (−5.8 %), iii) applying monocot-selective postemergence herbicides (−4.4 %), iv) relay temporal arrangement (−2.8 %), and v) with N and P fertilization rates above 150 and 35 kg ha-1, respectively. In relative terms, Brachiaria grass performance was more affected by i) intercropping adoption, with a reduced biomass penalty under a tropical climate (−63.9 %), ii) late sowing time for the intercrop (−59.5 %), iii) application of N fertilizer at a rate above 50 kg ha-1 (−70.5 %), and iv) non-use of postemergence herbicides (−21.9 %). Maize-Brachiaria grass intercropping was an effective alternative to produce residue (no-till system adoption) or forage (crop-livestock integrated system adoption) with reduced maize grain yield penalties, diversifying cropping systems in Brazil. Despite the production penalties for both crop species, considering different relative values, specific management practices and climate conditions could minimize yield penalties. Scenarios favoring maize yields may be preferred for intercropping systems focused on improving soil quality; in contrast, Brachiaria grass biomass may benefit the integration of crop-livestock systems focused on ensuring forage production. [Display omitted] • Intercropping decreased the productivity of maize by 5.6 % and of Brachiaria by 64 %. • The yield penalty varied across agronomic and environmental factors. • Sowing time and climate were key factors defining the performance of intercropping systems. • Intercropping was effective for the establishment of no-tillage systems. • Maize-Brachiaria grass intercropping is a way to implement crop–livestock systems. [ABSTRACT FROM AUTHOR]

The main cropping system in Brazil is soybean-maize off-season, particularly in tropical climate regions. However, there is a lack of information about the effects of alternative off-season crops on soybean performance and soil chemical fertility. The objective of this study was to evaluate, in a long-term experiment, the effects of off-season crops on soybean yield, seed protein and oil concentration, and soil chemical fertility under a no-tillage system. A seven-year experiment was conducted in Londrina, Paraná, Brazil. Treatments comprised six crop systems in the soybean off-season: (i) maize with nitrogen (N) fertilizer topdressing (80 kg N ha−1, (ii) maize without N fertilizer topdressing, (iii) wheat without N fertilizer topdressing, (iv) ruzigrass (Urochloa ruziziensis) without fertilizers, (v) showy rattlebox (Crotalaria spectabilis) without fertilizers, and (vi) unplanted fallow. Maize and wheat were used as cash crops and ruzigrass and showy rattlebox as cover crops. Ruzigrass had the highest straw production (average of 6.8 Mg ha−1 year−1) and improved soil fertility, especially organic carbon and potassium concentrations in the superficial soil layer. Ruzigrass and wheat off-season provided the highest soybean yields in succession (4311 and 4228 kg ha−1, respectively), whereas maize without N and fallow resulted in the lowest soybean yields (3841 and 3825 kg ha−1, respectively). Ruzigrass off-season provided the greatest yield stability of soybean and the fallow the lowest yield stability (coefficients of variation of 14.70 % and 23.78 %, respectively). The highest soybean seed protein concentration was observed with ruzigrass (368 g kg−1) and the lowest with fallow (353 g kg−1). The highest seed oil concentration was observed in maize with N and showy rattlebox (224 g kg−1 for both off-season crops) and the lowest with wheat (216 g kg−1). The ruzigrass provided the highest soybean seed protein and oil yields (1586 and 945 kg ha−1) and fallow the lowest (1352 and 845 kg ha−1). The ruzigrass used as soybean off-season cover crop improved the soil chemical fertility and soybean grain yield. • Ruzigrass in the off-season improves soybean yield and grain protein concentration. • Ruzigrass in the off-season improves soil fertility in the superficial layer. • Wheat is an adequate alternative as an off-season cash crop. • Maize without nitrogen topdressing, showy rattlebox, or fallow is not recommended. [ABSTRACT FROM AUTHOR]

This article presents a comparative ethnography of the smallholder agroforestry projects of an international environmental organization. Migrant ranchers in Brazil sell cattle from private properties in a heavily-deforested landscape. Indigenous farmers in Indonesia rely on subsistence food production on customary lands in a heavily-forested landscape. Despite these differences, the projects identify both migrant ranchers and indigenous farmers as "smallholders" and prescribe cash crop agroforestry as the solution to both their predicaments. In the face of expanding ranches and plantations, this cash crop solution accepts the destruction of forest ecosystems and livelihoods as inevitable, funneling smallholders into market agroforestry in agro-industrial landscapes. This article strengthens the case for comparative ethnography and challenges discursive conflations and political-economic biases of prevailing sustainable development policies. [ABSTRACT FROM AUTHOR]

Organismal distributions in human‐modified landscapes largely depend on the capacity of any given species to adapt to changes in habitat structure and quality. The golden‐headed lion tamarin (GHLT; Leontopithecus chrysomelas) is an Endangered primate from the Brazilian Atlantic Forest whose remaining populations occupy heterogeneous landscapes consisting primarily of shade cacao (Theobroma cacao) agroforestry, locally known as cabrucas. This cash crop can coexist with high densities of native tree species and holds a significant proportion of the native fauna, but its widely extolled wildlife‐friendly status is increasingly threatened by management intensification. Although this potentially threatens to reduce the distribution of GHLTs, the main determinants of tamarin's occupancy of cabrucas remain unknown, thereby limiting our ability to design and implement appropriate conservation practices. We surveyed 16 cabruca patches in southern Bahia, Brazil, and used occupancy modeling to identify the best predictors of GHLT patch occupancy. Key explanatory variables included vegetation structure, critical resources, landscape context, human disturbance, and predation pressure. We found a negative relationship between GHLT occupancy and the prevalence of jackfruit trees (Artocarpus heterophylus), which is likely associated with the low representation of other key food species for GHLTs. Conversely, cabrucas retaining large‐diameter canopy trees have a higher probability of GHLT occupancy, likely because these trees provide preferred sleeping sites. Thus, key large tree resources (food and shelter) are currently the main drivers of GHLT occupancy within cabruca agroecosystems. Since both factors can be directly affected by crop management practices, intensification of cabrucas may induce significant habitat impacts on GHLT populations over much of their remaining range‐wide distribution. Research Highlights: Key habitat resources (food and sleeping sites) are the main drivers of golden‐headed lion tamarin (GHLT) occupancy in cabrucas, and they are affected by management practices. Intensification of management can induce significant impacts on GHLT persistence in cabrucas in much of its remaining habitat. [ABSTRACT FROM AUTHOR]

• Net nitrification rates did not differ among forage grasses in two growing seasons. • Maize grain yield may be impaired when grown after ruzigrass. • Forage grasses had no effect on N recovery in the plant–litter–soil system. • N recovery in maize and soil averaged 35% and 46%, respectively, in the first season. • Recovery of residual labeled N in maize was, on average, 2.9% in the second season. Tropical forage grasses of the genus Megathyrsus and Urochloa can suppress soil–nitrification by releasing inhibitory substances, reducing N losses and increasing fertilizer N recovery of the cash crop in rotation. In contrast, ruzigrass (Urochloa ruziziensis) has been reported to decrease the yield and N accumulation of the subsequent crop and hence can affect N use efficiency and the fate of applied N. We investigated the effects of Guinea grass (M. maximum), palisade grass (U. brizantha), and ruzigrass on succeeding crop yield, N accumulation, and the fate of 15N–labeled fertilizer applied to maize (Zea mays L.) in a 2–year field experiment in Brazil. Maize was fertilized with 140 kg ha–1 N as (15NH 4) 2 SO 4 or not fertilized, and recovery of residual 15N was quantified in the second season. Net nitrification rates through an incubation study had no differences among grasses. Nitrogen application increased maize yield and N accumulation in both seasons, whereas maize yield decreased by 9.5% following ruzigrass compared with the other forages. The grasses had no effect on 15N recovery by maize or in the system. On average, the recovery of 15N in maize and soil was 34% and 46% in the first growing season and 2.9% and 20% in the second season, respectively. Our results indicated that tropical perennial grasses had no differential effects on nitrification rates and the fate of 15N–labeled fertilizer in the plant–litter–soil system in the season of application nor in the subsequent crop (residual effect). [ABSTRACT FROM AUTHOR]

Crop rotations with high plant diversity and biomass input have been recognized worldwide as a crucial practice for increasing the sustainability of grain production systems, particularly in regions under no-tillage (NT) management. Nonetheless, low-diversity grain production systems based on double cropping (two crops in the same agricultural year) repeated over time, including soybean followed by maize (known in Brazil as "second crop maize") or wheat, remain prevalent in Brazil. The continuous use of these systems can impair soil yield capacity, farmers' profits, and environmental sustainability. Therefore, this study aimed to verify the grain yield and profitability of different production systems with different levels of plant diversity. This study was based on results obtained during the 2009–2017 cropping seasons through a long-term field trial conducted under NT since 1985 in southern Brazil. The trial covered two 4-year agricultural cycles with two crops per year, resulting in eight crops per cycle and 16 crops over the entire period. The experiment followed a randomized complete block design, with five treatments and four replicates. The treatments involved three diversified crop rotations, comprising different cover crops and two double-crop systems (wheat-soybean and maize-soybean). For a given agricultural year, wheat and cover crops (white oats, black oats, and forage radish) were grown from May to September, and the second crop maize was grown from March to August. Soybean and first crop maize were grown during the summer from October to February. The grain yield, gross revenue, production cost, and cumulative profit were analyzed for each production system. Gross revenue and profit were primarily estimated based on the actual annual average commodity prices received by farmers, and two additional price scenarios (pessimistic and optimistic) were proposed considering the average prices from 2010 to 2017. Regardless of the cropping season, first crop maize and wheat grain yields were higher in diversified crop rotations. The production system only affected the second crop maize yield in 2010/2011, with a higher value obtained in a diversified crop rotation system. The soybean yield in diversified crop rotations was higher than that in double-crop systems. Considering each cash crop separately, soybean produced the highest average profit (US$ 472.50 ha−1), followed by the first crop maize (US$ 245.31 ha−1) and wheat (US$ 77.71 ha−1), whereas the second crop maize led to economic losses (−US$ 121.73 ha−1). All diversified crop rotations produced a higher 8-year cumulative profit and gross margin than the maize–soybean in double-crop system. The relative economic performance of production systems remained unchanged under alternative price scenarios (pessimistic and optimistic) compared with that under the observed (actual) price scenario. However, the cumulative profit of maize and soybean in double-crop system was the most negatively impacted in the pessimistic scenario (−45.9%), indicating greater economic risk. Overall, lack of direct revenues from cover crops were compensated by increased grain yield in the spring-summer season and profitability of diversified crop rotation systems. Therefore, diversified crop rotation systems are economically competitive with double crop systems, rendering them feasible management options for conserving natural resources and increasing crop resilience to adverse climatic conditions. • Diversified crop rotation improves grain yield. • Diversified crop rotation allows sustainable intensification of agricultural systems. • Diversified crop rotation increases soybean productivity. • Diversified crop rotation increases productivity and profitability. • Diversified crop rotation can help farmers boost production and grow profits. [ABSTRACT FROM AUTHOR]

We analyze changes in the extent of slash and burn cultivation (SBC) and shifting cultivation (SC) and the main drivers of change observed in the last 10 years across the Brazilian Amazon. Our results show that SC is stable in indigenous andcaboclocommunities from Amazonas and Acre. SBC increases along new roads, illustrating how roads shape deforestation frontiers beyond the “arc of deforestation.” In established forest frontiers, the conversion of forests into pasture or cash crops through SBC continues to increase locally, but smallholders' diversification strategies translate into complex land uses with both the increase and decrease of SBC and SC observed locally. Secure land tenure, access to markets, and population increase appear to be driving to the classic intensification path. Overall, access to cash transfer programs has helped stabilize forest frontiers as households become less reliant on subsistence agricultural production. [ABSTRACT FROM PUBLISHER]

Estimates of natural resource harvests often inform rural conservation and development strategies. Retrospective household surveys remain one of the most commonly employed methods for estimating harvests. Pair-wise comparisons of estimates from household surveys versus diary records were performed for household harvests in the Brazilian Amazon. Although diaries and surveys produce similar estimates of mean economic value for different product groups, 33% of product-level estimates showed a three-fold difference between methods with no consistent patterns in discrepancy direction. Significant differences in estimates for highly valued products (cash crops, game animals, and fish) together with higher respondent confidence in diaries may undermine household models based exclusively on surveys. [Copyright &y& Elsevier]

Due to the complexity of management of plant-parasitic nematodes in cash crops, the use of non-chemical methods, such as rotation with green manures, has increased in recent years. However, data about the host status of green manures for lesion nematodes are scarce. Thus, two glasshouse trials were carried out to evaluate the host status of some green manures for two isolates of Pratylenchus brachyurus, a root-lesion nematode often found attacking soybean, maize and cotton in Brazil. Green manures tested were pigeon pea (Cajanus cajan) cultivars Fava Larga and Iapar 43, Crotalaria juncea, C. spectabilis, C. mucronata, C. breviflora, C. ochroleuca, C. paulina, velvetbean (Mucuna pruriens) cvs Black, Dwarf and Gray. Soybean cv. Pintado and French marigold (Tagetes patula) were included as standard good and poor hosts for P. brachyurus. In a separate glasshouse experiment, a naturally infested soil was used to evaluate the suitability of two green manures to P. brachyurus in comparison with two gramineaceous cover crops. In addition, morphometric studies were carried out with the two isolates of P. brachyurus used in experiments in order to confirm the species. Among the 11 green manures tested, at least two, C. spectabilis and C. breviflora, can be useful as rotation crops to reduce population densities of P. brachyurus, irrespective of the origin of the nematode. By contrast, all velvetbean cultivars and C. juncea must be avoided in infested areas as they are good hosts for the nematode. [ABSTRACT FROM AUTHOR]

Weeds are a concern to farmers mainly by reducing crop yield, especially in organic farming where herbicides are not an option. Additionally, reducing reliance on herbicides is among the goals to achieve sustainable crop production. By investigating alternatives for weed control, several studies have shown that grassland is more competitive with weeds than cash crops and adopting diversified crop rotations reduces overall weed infestation. However, in many of those studies the effect of the rotation is confounded with herbicide use. Moreover, there is a gap in understanding how diversified rotations influence the weed community and how changes in that weed community impact yield of the subsequent cash crop. Here, using a 4-year herbicide-free experiment in southern Brazil, we compared a grassland-cropping rotation (i.e., 3-year perennial tropical grassland before maize cultivation) vs. a crop-based rotation (i.e., sunflower-maize) to clearly characterize how a more diversified crop rotation changed weed patterns and weed interference in maize. We demonstrate the higher suppressive effect on weeds of a grassland-cropping rotation compared with a crop-based rotation, clearly evidenced in the early season of maize growth, in which the crop-based rotation had about twice as many number of weeds as the grassland-cropping rotation. However, there was no difference in seedbank size between both rotations. Weed community composition was not affected (i.e. rotations had 98% similarity in species composition), but weed assemblage was drastically changed with different rates of species-specific infestation in each rotation. The crop-based rotation selected weeds with rapid light acquisition ability (higher specific leaf area) that added to higher early season weed infestation and higher competitive pressure of weeds resulted in maize grain yield losses, whereas there was no significant weed interference on maize grain yield in the grassland-cropping rotation. The strategy of including a tropical grassland in rotation with cash crops as a herbicide-free weed management tool reduces overall weed infestation and prevents selection of weeds that cause a significant yield reduction in maize and represents an economically viable alternative. [ABSTRACT FROM AUTHOR]

Weeds are a major constraint on food and feed production, and the excessive use of herbicides to control them is a global concern for food security, human health, and environmental sustainability. Under no-tillage systems, cover crop residues provide a physical barrier to weed emergence that reduce weed infestations and reliance on herbicides. In integrated crop-livestock systems, cover crops provide fodder to grazing animals, adding an additional source of revenue for farmers; however, grazing can cause a trade-off because it reduces biomass during the cover crop season and residues left on the soil surface in the next cash crop, which may increase weed infestation. In the current study, it was hypothesized that there is an optimal cover crop forage allowance during the grazing period that maximizes beef production while retaining enough cover crop biomass and residue to minimize weed infestations and maintain grain yield of the subsequent cash crop. Therefore, the effects of cover crop (mixed black oat + Italian ryegrass) forage allowances (based on sward height) during the winter grazing period on weed infestations, beef production, and soybean grain yield during the next summer season were evaluated. The experiment was conducted in several commercial fields involving two experimental protocols (one short-term and one long-term experiment) in Southern Brazil, and the results demonstrated that a moderate forage allowance in winter cover crops (i.e., maintaining 17.8 cm of winter grazed cover crop sward height) reduced weed infestations and increased soybean and beef production when compared with a lower forage allowance (i.e., < 10.7 cm of winter grazed cover crop sward height) or a higher forage allowance (i.e., > 17.8 cm of winter grazed cover crop sward height). Therefore, the current study provides evidence that it is possible to optimize forage allowance to sustainably intensify arable cropping systems using winter cover crops for direct grazing. [ABSTRACT FROM AUTHOR]