Smallholder farmers in low-income countries often use plant extracts (‘botanicals’) to prepare homemade pesticides. This practice has remained controversial due to a perceived lack of evidence that such home remedies are effective and safe. Scientists Dougoud et al. reviewed commonly used botanicals and found evidence that they can reduce pests and crop damage. However, results are highly variable, depending on how the homemade pesticides are prepared and used.
The expansion of renewable energies aims at meeting the global energy demand while replacing fossil fuels. However, it requires large areas of land, leading to competition for limited land resources. Agrophotovoltaic systems can spare land resources by combining food and solar energy productions. Scientists Weselek et al. recently reviewed that such synergetic combination might increase overall land productivity by up to 70%. They concluded that agrophotovoltaic systems can be a valuable technical approach for more sustainable agriculture.
Vermicomposting is a process whereby earthworms transform organic residues into compost used as a growing substrate for plants. Scientists Blouin et al. recently showed that on average, vermicompost increased by 26% the commercial yield of cultivated plants. Cattle manure appeared the best original material, and the effect of vermicompost was stronger when no fertilizer was added.
Sustainable nutrient management requires timely diagnostic of crop nutrition status to support yield while avoiding over- and under-fertilization and their associated environmental impacts. Lemaire et al. reviewed the concept of N, P, and K accumulation in proportion to crop growth and their allocation within plants and canopies. They show their potential usage to diagnose crop nutrition status, to analyze genotype-environment-management interactions driving crop yield and to phenotype crops.
Sustainable intensification of agricultural production is needed to ensure increased productivity but for farmers, this may alter the yield-to-labor ratio. Scientists Dahlin and Rusinamhodzi recently reviewed the relationship between maize grain yield change and labor input for a range of practices proposed for sustainable intensification of smallholder farms in sub-Saharan Africa. They show that the examined options may increase both crop yield and labor demand for smallholder farmers.
Insects can be useful allies to sustainably manage organic wastes. They constitute also alternative sources of proteins and fats for humans. Scientists Fowles and Nansen recently reviewed the potential for using insects to convert wastes into value-added materials. After describing the “ideal insect bioconverter”, they conclude that targeted breeding of insects and their gut microbes is necessary to convert specific waste streams. More research is needed to explore the existing insect diversity and to identify new bioconverter species.
Sustainably intensifying smallholder farming systems on sandy soils is critical to the development of livelihoods in the Mekong region of Cambodia and Laos. Scientists Philp et al. recently reckoned that forages could intensify livestock production in rainfed lowland rice farming systems. Varieties must be adapted to both flooding and drought. Furthermore, soil acidity, low soil fertility, drought and the continual removal of nutrients in harvested forage must be carefully managed.
Millions of hillside farmers around the world cultivate crops on narrow terraces, whose walls are often underutilized. Scientists Chapagrain et al. recently showed that cultivation of wall-climbing crops (e.g. chayote squash, pumpkin, yam) and wall-descending crops (e.g. ricebean, cowpea, horsegram, blackgram) can enhance economic returns to farmers. The adoption of this promising practice can improve the ecosystems and the well-being of terrace farmers.
More diversified farms can render food systems sustainable, resilient and socially just. Scientists Valencia et al. showed that the National School Feeding program in Brazil generated a large and diversified demand for vegetables and legumes. As a consequence, it transformed low diverse & high input farming systems into diversified horticultural productions and increased the hectarage of land under diversified farming systems.
In southern Brazil, pastures with mixed oat/ryegrass during winter are directly planted with soybean in summer. Scientists Peterson et al. found that pastures grazed by beef cattle during winter exhibited drier soil in the following summer. However, soybean productivity was unchanged. Long term crop-livestock integration induces unique synergies which need to be considered to ensure the sustainability of these systems.