Balanço de nitrogênio, fósforo e potássio na agricultura da América Latina e o Caribe

Abstract

The objective of this study was to evaluate nutrient consumption and exports in agricultural systems of Latin America and the Caribbean (ALC) in order to estimate the balance of the main macronutrients (N, P and K) used by crops. The nutrient balance was estimated by considering the amount of nutrients entering the agricultural systems via fertilization and biological N2 f ixation (BNF) and the amount of nutrients leaving the systems through crop harvest removal in each country. Based on off icial statistics for the year 2016, the ALC region presented a positive balance of nitrogen. However, some countries (Argentina, Bolivia and Paraguay) had a negative balance of N. Biological N2 f ixation is the main source of N in Latin American agriculture, accounting for more than 62% (11.29 Mt N) of the total N (18.10 Mt N) entering the agricultural systems. Broadly speaking, the supply of P via fertilizer in Latin America counterbalanced the removal through crop harvest, with the exception of Argentina, Bolivia, Guatemala and México, which have crop production dependent on soil P mining. Potassium was one of the nutrients whose application does not meet the demand of the region’s crops, presenting negative balances in almost all countries except Brazil, Colombia and Venezuela. Nevertheless, it should be noted that many agricultural soils from this region have naturally high K availability. Greater care in the use of inputs, including fertilizers, occurs with cropping soybean, corn, coffee, sugarcane and oranges, while the rest are dependent on natural soil fertility, which may compromise food safety.

Nutrient stocks, flows and balances for the Bolivian agri-food system: Can recycling human excreta close the nutrient circularity gap?

“…A mass balance for nitrogen and phosphorus was performed for the Bolivian agri-food system (i.e., crop cultivation and human consumption). Based on the results of the mass balance, indicators of nutrient sufficiency (Guareschi et al, 2019) and circularity (Papangelou and Mathijs, 2021) for crop cultivation were calculated. Subsequently, the potential of nutrients contained in human excreta to supply the nutrients required for crop cultivation was estimated.…”

“…We conducted an evaluation of the current nutrient stocks, flows, and budgets for the Bolivian agri-food system at two geographical scales, national and regional. We quantified the current nutrient demand in terms of indicators for sufficiency (Guareschi et al, 2019) and circularity (Papangelou and Mathijs, 2021) and assessed the potential of renewable stocks (human excreta and livestock manure) to meet the nutrient deficit in the system. Our findings have implications for food and nutrition security policy in low-and middle-income countries.…”

Fatores que afetam a disponibilidade de micronutrientes no solo

“…A adsorção dos micronutrientes é um processo de adesão deles aos coloides do solo suficientemente forte, sendo considerado importante no controle da sua abundância e passagem na solução do solo e, consequentemente, na sua disponibilidade para as plantas [28]. As perdas de nutrientes do solo se devem à alguns fatores, tais como erosão, lixiviação, volatilização, nitrificação, dentre outros, fazendo com que aumente a demanda do solo por esses nutrientes [29].…”

Advancement of Nitrogen Fertilization on Tropical Environmental

“…Between 95 and 100% of the total N input into soil is from the surface through rainfall or dust and aerosols, irrigation, runoff and groundwater, biological fixation by phototrophic and heterotrophic organisms, organic and inorganic fertilization, and seed reserves. Besides the plants exports, the N output occurs by erosion, leaching and drainage, ammonia volatilization, denitrification, and senescence plants [21,22].…”