The input reduction principle of agroecology is wrong when it comes to mineral fertilizer use in sub-Saharan Africa

Gatien Falconnier Marc Corbeels Frédéric Baudron Antoine Couëdel leonard rusinamhodzi bernard vanlauwe Ken Giller (2023, [Artículo])

Can farmers in sub-Saharan Africa (SSA) boost crop yields and improve food availability without using more mineral fertilizer? This question has been at the center of lively debates among the civil society, policy-makers, and in academic editorials. Proponents of the “yes” answer have put forward the “input reduction” principle of agroecology, i.e. by relying on agrobiodiversity, recycling and better efficiency, agroecological practices such as the use of legumes and manure can increase crop productivity without the need for more mineral fertilizer. We reviewed decades of scientific literature on nutrient balances in SSA, biological nitrogen fixation of tropical legumes, manure production and use in smallholder farming systems, and the environmental impact of mineral fertilizer. Our analyses show that more mineral fertilizer is needed in SSA for five reasons: (i) the starting point in SSA is that agricultural production is “agroecological” by default, that is, very low mineral fertilizer use, widespread mixed crop-livestock systems and large crop diversity including legumes, but leading to poor soil fertility as a result of widespread soil nutrient mining, (ii) the nitrogen needs of crops cannot be adequately met solely through biological nitrogen fixation by legumes and recycling of animal manure, (iii) other nutrients like phosphorus and potassium need to be replaced continuously, (iv) mineral fertilizers, if used appropriately, cause little harm to the environment, and (v) reducing the use of mineral fertilizers would hamper productivity gains and contribute indirectly to agricultural expansion and to deforestation. Yet, the agroecological principles directly related to soil fertility—recycling, efficiency, diversity—remain key in improving soil health and nutrient-use efficiency, and are critical to sustaining crop productivity in the long run. We argue for a nuanced position that acknowledges the critical need for more mineral fertilizers in SSA, in combination with the use of agroecological practices and adequate policy support.

Manure Crop Yields Smallholder Farming Systems Environmental Hazards CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA BIOLOGICAL NITROGEN FIXATION LEGUMES NUTRIENT BALANCE SOIL FERTILITY AGROECOLOGY YIELD INCREASES LITERATURE REVIEWS

Climate robust soil fertility management by smallholders in Africa, Asia, and Latin America

Tek Sapkota (2023, [Objeto de congreso])

CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA SOIL FERTILITY SMALLHOLDERS FERTILIZERS NUTRIENT MANAGEMENT

Nepal Seed And Fertilizer Project

Dyutiman Choudhary (2022, [Objeto de congreso])

CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA SEED FERTILIZERS SEED INDUSTRY PRIVATE SECTOR MAIZE RICE INTEGRATED SOIL FERTILITY MANAGEMENT COVID-19

Nepal Seed And Fertilizer Project

Dyutiman Choudhary (2021, [Objeto de congreso])

CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA SEED SEED INDUSTRY PRIVATE SECTOR MAIZE RICE INTEGRATED SOIL FERTILITY MANAGEMENT COVID-19

Hacia un manejo sustentable de la quinua en el altiplano sur de Bolivia

Santiago Lopez-Ridaura Ravi Gopal Singh (2022, [Libro])

CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA QUINUA FERTILIDAD DEL SUELO GANADERÍA AGRICULTURA DE CONSERVACIÓN SUELO SIEMBRA PLAGAS QUINOA SOIL FERTILITY ANIMAL HUSBANDRY CONSERVATION AGRICULTURE SOIL SOWING PESTS

Soil analysis and integrated nutrient management

Isaiah Nyagumbo (2021, [Objeto de congreso])

CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA SOIL ANALYSIS NUTRIENT MANAGEMENT SOIL FERTILITY

Manejo de pasturas para la crianza de llamas

Santiago Lopez-Ridaura Ravi Gopal Singh (2022, [Libro])

Pasturas CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA AGRICULTURA DE CONSERVACIÓN GANADERÍA ARBUSTOS LEGUMINOSAS FORRAJES PASTOREO SUELO CAMBIO CLIMÁTICO CONSERVATION AGRICULTURE ANIMAL HUSBANDRY SHRUBS LEGUMES FORAGE GRAZING SOIL CLIMATE CHANGE LLAMAS AGACHO

Arbustos y pastos para restablecer la cobertura vegetal en zonas áridas del Sur de Bolivia

Santiago Lopez-Ridaura Ravi Gopal Singh (2022, [Libro])

Pastos CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA AGRICULTURA DE CONSERVACIÓN SUELO COBERTURA DE SUELOS FERTILIDAD DEL SUELO CAMBIO CLIMÁTICO GANADERÍA VEGETACIÓN ARBUSTOS CONSERVATION AGRICULTURE SOIL LAND COVER CLIMATE CHANGE ANIMAL HUSBANDRY VEGETATION SHRUBS

Application of ammonium to a N limited arable soil enriches a succession of bacteria typically found in the rhizosphere

Yendi Navarro-Noya Marco Luna_Guido Nele Verhulst Bram Govaerts Luc Dendooven (2022, [Artículo])

Crop residue management and tillage are known to affect the soil bacterial community, but when and which bacterial groups are enriched by application of ammonium in soil under different agricultural practices from a semi-arid ecosystem is still poorly understood. Soil was sampled from a long-term agronomic experiment with conventional tilled beds and crop residue retention (CT treatment), permanent beds with crop residue burned (PBB treatment) or retained (PBC) left unfertilized or fertilized with 300 kg urea-N ha-1 and cultivated with wheat (Triticum durum L.)/maize (Zea mays L.) rotation. Soil samples, fertilized or unfertilized, were amended or not (control) with a solution of (NH4)2SO4 (300 kg N ha-1) and were incubated aerobically at 25 ± 2 °C for 56 days, while CO2 emission, mineral N and the bacterial community were monitored. Application of NH4+ significantly increased the C mineralization independent of tillage-residue management or N fertilizer. Oxidation of NH4+ and NO2- was faster in the fertilized soil than in the unfertilized soil. The relative abundance of Nitrosovibrio, the sole ammonium oxidizer detected, was higher in the fertilized than in the unfertilized soil; and similarly, that of Nitrospira, the sole nitrite oxidizer. Application of NH4+ enriched Pseudomonas, Flavisolibacter, Enterobacter and Pseudoxanthomonas in the first week and Rheinheimera, Acinetobacter and Achromobacter between day 7 and 28. The application of ammonium to a soil cultivated with wheat and maize enriched a sequence of bacterial genera characterized as rhizospheric and/or endophytic independent of the application of urea, retention or burning of the crop residue, or tillage.

CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA AMMONIUM CROP RESIDUES WHEAT MAIZE TILLAGE SOIL

The fate of rice crop residues and context-dependent greenhouse gas emissions: Model-based insights from Eastern India

Sonam Sherpa virender kumar Andrew Mcdonald (2024, [Artículo])

Crop residue burning is a common practice in many parts of the world that causes air pollution and greenhouse gas (GHG) emissions. Regenerative practices that return residues to the soil offer a ‘no burn’ pathway for addressing air pollution while building soil organic carbon (SOC). Nevertheless, GHG emissions in rice-based agricultural systems are complex and difficult to anticipate, particularly in production contexts with highly variable hydrologic conditions. Here we predict long-term net GHG fluxes for four rice residue management strategies in the context of rice-wheat cropping systems in Eastern India: burning, soil incorporation, livestock fodder, and biochar. Estimations were based on a combination of Tier 1, 2, and 3 modelling approaches, including 100-year DNDC simulations across three representative soil hydrologic categories (i.e., dry, median, and wet). Overall, residue burning resulted in total direct GHG fluxes of 2.5, 6.1, and 8.7 Mg CO2-e in the dry, median, and wet hydrologic categories, respectively. Relative to emissions from burning (positive values indicate an increase) for the same dry to wet hydrologic categories, soil incorporation resulted in a −0.2, 1.8, or 3.1 Mg CO2-e change in emissions whereas use of residues for livestock fodder increased emissions by 2.0, 2.1, or 2.3 Mg CO2-e. Biochar reduced emissions relative to burning by 2.9 Mg CO2-e in all hydrologic categories. This study showed that the production environment has a controlling effect on methane and, therefore, net GHG balance. For example, wetter sites had 2.8–4.0 times greater CH4 emissions, on average, than dry sites when rice residues were returned to the soil. To effectively mitigate burning without undermining climate change mitigation goals, our results suggest that geographically-target approaches should be used in the rice-based systems of Eastern India to incentivize the adoption of regenerative ‘no burn’ residue management practices.

Soil Carbon Rice Residue Burning Life Cycle Assessment CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA SOIL CARBON RICE LIFE CYCLE GREENHOUSE GASES CLIMATE CHANGE