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- 1. Nutrient Balance andSoil Quality in Agroecosystems Fernando O. García fgarcia1957@gmail.com @garciaf_nutri Concepción, 21 March 2023
- 2. Why nutrient balanceand soil quality/health? • Soils are involved in most of SDGs • One Health: soil + plants + animals + humans + environment (Lal, 2021) • Soils and human health: food production, C sequestration, detoxification, water and nutrient retention, biodiversity (Brevik et al., 2020).
- 3. Outline •Introduction: Some definitionsand scope •Field crop systems of South America •Soil quality/health status, threats and challenges •Nutrient balances at different countries/regions •Management to maintain/improve soil health and nutrient balances
- 4. What is SoilQuality/Health? “the ability of the soil to sustain the productivity, diversity, and environmental services of terrestrial ecosystems” Intergovernmental Technical Panel on Soils (ITPS, 2020)
- 5. Soil fertility • …is the ability of a soil to sustain the growth of plants by providing essential nutrients and favorable chemical, physical and biological characteristics as a habitat for their growth (FAO, 2019) FAO (2019,2022)
- 6. Indicators of nutrientuse efficiency (Dobermann, 2007; Norton et al., 2015) Indice Estimation Typical levels for N (maize or wheat) Agronomic efficiency (AE) (Y-Y0)/F 10-30 kg grain/kg nutrient Recovery efficiency (RE) (U-U0)/F 30-50% ∆ kg nutrient uptake/kg applied nutrient Partial Productivity Factor (PPF) Y/F 40-80 kg grain/kg nutrient Partial Nutrient Balance (PNB) R/F >1.00 = Deficit <1.00 = Excess kg grain nutrient /kg nutrient Y= yield, F = fertilization, R = removal, U= uptake scale and objective use of the index … always an output/input ratio
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- 8. Pampas Cerrados Amazonas South central Brazil Great Chaco Centralvalleys of Chile WRB, FAO (2014) Andes (highlands and valleys) Volcanic soils of southern Chile Main soil health challenges • Wind and water erosion • Soil organic matter (SOM) depletion • Nutrient losses • Soil compaction • Salinization • Biodiversity losses • Contamination South America soils and agroecosystems Erosion - Ecuador M. Ramos Erosion Alto Paraná, Paraguay K. Moriya, 2011 Uruguay Argentina Río de la Plata Océano Atlántico Eutrophication Rio de la Plata L. Carrasco, 2015 Expansion into fragile ecosystems Carmen de Patagones, Argentina D. Iurman, INTA Ascasubi, 2009 Expansion into fragile ecosystems “Chaqueos” at Bolivia F. Garcia Salinization Santa Cruz, Bolivia M. S. Viera, 2014 Compaction G. Cordone y G. Gerster INTA Casilda y Roldán, 2005
- 9. Soil nutrient budgetsper cropland area, 2018 FAOSTAT Soil nutrient budget, 2021
- 10. 0.0 1.0 2.0 3.0 4.0 5.0 Argentina Bolivia BrasilParaguay Uruguay Australia Canada EE.UU. Relación Remoción/Aplicación (BPN) N P K Removal to Application Ratio (PNB) for N, P, and K at Argentina, Bolivia, Brazil, Paraguay and Uruguay, and comparison with other countries Elaborated from Fertilizar AC and Minagro (2017-19), FAOSTAT, ANAPO, da Cunha et al. (2018), Causarano (2017), update 2020 from Mancassola and Casanova (2015), Edis et al. (2012), NuGIS-IPNI (2012) Removal to Application Ratio (PNB) Application > Removal Removal > Application US
- 11. Adapted from EUNitrogen Expert Panel (2015) NUE 90% = PPF 80 kg grain/kg N Maximum excess 80 kg N NUE 60% = PPF 50 kg grain/kg N NUE 30% = PPF 25 kg grain/kg N “Ideal” Contamination risk Soil degradation risk … how are Nitrogen Use Efficiencies (NUE) in maize … Partial Productivity Factor of N (PPF-N) = Yield / N rate Argentina Brasil Bolivia Paraguay Uruguay Chile Perú México N rate (kg/ha) Maize yield (kg/ha) NUE30 NUE60 NUE90
- 12. Pillars of sustainablesoil management for improved soil health Rotations + No-tillage + Cover crops + Balanced nutrition Studdert et al., 1997; Studdert and Echeverria, 2000; Ernst and Siri-Prieto, 2009; Novelli et al., 2013; Sá et al., 2014, 2017; Nunes et al., 2020; Carvalho et al., 2021; Gabbarini et al., 2021; Nicoloso and Rice, 2021; Rui et al., 2022; Mikha and Marake, 2022; Pires et al., 2023 Soil organic carbon as the comprehensive soil health/quality indicator Rotations/cropping intensity • Crop diversity • Pasture/crop rotations • Santa Fe system, agriculture/livestock integration No-tillage • Minimum disturbance • Reduce erosion • Soil C increases and stratification • Improved soil microbial biomass and activity Cover crops • Root and microbial diversity • Improved soil structure • N fixation • Reduce erosion • Weed control Balanced nutrition • Improved yields • Improved soil carbon • Improved soil microbial biomass and activity
- 13. Rotations + Balancednutrition Long-term experiment at INIA La Estanzuela (Uruguay) Agricultural diversification and intensification lead to 30% higher crop yields and 19% greater SOC Cont ag Cont ag Fert 33% Ag 66% Past Cont ag Cont ag Fert 33% Ag 66% Past Soil Organic Carbon (g/kg) Accumulated grain yield (Mg/ha) Grahmann et al., 2020
- 14. Sá, et al.,Land Degradation and Development, 2015 Sequestered C = 0.423 + 0.165 C R² = 0.83 p = 0.0006 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 Annual C gain (Mg ha -1 ) Annual C input (Mg ha-1) Carbon restoration by no-till cropping systems in oxisolls of Brazil Sá et a. (2015) Cropping intensity + No-tillage Brachiaria and other cover crops Santa Cruz, Bolivia ” … NT cropping systems with high C input have a large potential to reverse the process of soil degradation and SOC decline.”
- 15. Nutrition network CREASouthern Santa Fe (2000-19) – García et al. (2022, 2023) Balanced NPS nutrition contributes 15% to 47% to crop yields in the central Pampas of Argentina Bulk density tend to decrease under balanced NPS nutrition Improving nutrient balances: Effects on yields and soil health in long-term experiments 41% 51% 29% 15% 40% 47% 27% 15% 9% 9% 14% 6% 10% 26% 12% 7% 25% 25% 6% 3% Maize Wheat DC Soybean FS Soybean Relative response (%) N P S NPS NPS+Micros 1 1.1 1.2 1.3 1.4 1.5 2003 2012 2021 Bulk density (g cm -3 ) Reference Check NPS 1 1.1 1.2 1.3 1.4 1.5 2003 2012 2021 Bulk density (g cm -3 ) Reference Check NPS Balducchi - Teodelina, Santa Fe La Blanca - A. Ledesma, Córdoba
- 16. Conceptual relationships betweenN fertilizer input and maize yield, residue production, and residual soil inorganic N Poffenbarger et al. (2017) - https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0172293 Would balanced nutrition always improve yield and soil health/quality? High nutrient use efficiency Low nutrient use efficiency AONR = Agronomic Optimum Nitrogen Rate
- 17. Improving soil healththrough a systemic and integral approach to soil fertility… üDecoupling ag production from externalities Adapted from Moraes Sá and Rice Oats Oats Soybean Soybean Wheat Corn Crop Residues Continuous C Flux Organic compounds MBC e MBN; humic compounds Active Pool Slow Pool Passive Pool Bulk Density; SOC and N pools Soil carbon pool C; DpH; CTC; P e K physical, chemical and biological properties Intensification and Diversification Soil Organic Carbon Microbial Activity Nutrient Cycling Soil Structure Soil Biodiversity Water Erosion & Availability Gaseous Emissions Plant Growth Yield Environmental Services Sustainability Rice (2018)
- 18. Conceptual model ofSoil Quality Index (SQI) in BioAS SQI Fertbio Soil organic matter CEC Acidity (H+Al, Al+3) Supply of K, Ca, Mg, cation saturation β-Glicosidase Arilsulfatase Nutrient cycling Nutrient storage Nutrient supply Biological SQI = Chemical SQI Value from 0 to 1 P supply I. C. Mendes et al., 2021
- 19. Thank you! Fernando O.García fgarcia1957@gmail.com @garciaf_nutri