Cover crops are gaining in popularity for their positive effects in agroecosystems, especially under organic farming and in low-input agriculture. Based on a 3-year field experiment, scientists Scavo et al. found that self-residing subterranean clover with the incorporation of dead mulches into the soil reduced weeds and increased the soil nitrogen. These results are useful for reducing the utilization of synthetic herbicides and mineral nitrogen fertilizers in Méditerranéenne orchards.
Intercropping or cultivating simultaneously more than one species on the same land is a means of improving resource use in agriculture. In a recent analysis, scientists Jensen et al. revealed that intercropping grain legumes with cereals could reduce the requirement for synthetic N-fertilizer by 26% on a global scale, thus allowing important net land saving. Intercropping supports, therefore, the development of more sustainable cropping systems.
Agriculture has to reduce synthetic inputs. Consequently, ecological processes and alternative agricultural practices will become the main regulators of carbon (C), nitrogen (N) and phosphorus (P) in cropped soils. Scientists Bertrand et al. recently observed that soil C storage is constrained by N and P supplies in various agricultural situations. Several agroecological practices that improve nutrient recycling can resolve this constraint.
In sub-Saharan Africa, rapid-growing cities generate increasing volumes of organic wastes that can be recycled and transformed into organic fertilizers. Scientists Thuriès et al. found considerable variability and discrepancy in both agronomic and economic values of these wastes. Their results suggest that the composting process needs to be improved. They reckoned that the humus potential should be calculated to assess more accurately the amendment value and used to adjust their market price.
Biochar is a technology proposed to mitigate climate change, improve soil fertility, energy production, and organic waste treatment. Scientists Müller et al. showed how a place-based assessment and a local knowledge analysis allow designing sustainable biochar systems in South India. Combined with agronomical and biogeochemical evaluations of the biochar effect on soil, this new approach will improve biochar development in tropical regions and beyond.
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.
In tropical agroforestry systems, the appropriate nutrient prescription is a challenge due to natural environmental heterogeneity and variable nutrient acquisition strategies between species. Scientists Borden and Isaac used a novel approach to monitor root response of cocoa to fertilizers. They showed that the analysis of root trait expression can be used to improve nutrient management in agroforestry systems.
The immature (i.e. unproductive) period of rubber tree plantations is the most critical period for nutrient management and a key determinant of future yields. Scientists Vrignon-Brenas et al. reviewed current fertilization practices, soil management and nutrient dynamics in immature plantations. Improvement is possible by use of agroecological practices such as intercropping and the development of a nutrient budget approach.
Fertilisers based on recovered phosphorus from secondary raw materials can provide an alternative to mined rock phosphate fertilisers in line with the circular economy. Scientists Huygens and Saveyn found that agronomic efficiency of selected fertilisers derived from secondary raw materials may compare with mined rock phosphate and processed fertilisers, in settings relevant for European agriculture.
Identifying optimum nitrogen fertilizer application rate is critical for sustainable farm management. Scientists Mesbah et al. developed a method, called Identifying NEMO, to diagnose an environmentally friendly optimum rate using crop models. They tested the method in the predominant Canadian corn production region where there exists a gradient of agroclimatic conditions. Eventually, they suggest novel strategic N recommendations.