ZONEAMENTO DE RISCO CLIMÁTICO PARA CULTIVO DA SOJA NO CERRADO

A agricultura e uma atividade de risco e incerteza. O Zoneamento Agricola de Risco Climatico (ZARC) indica o que, onde e quando plantar para fugir dos eventos climaticos. O objetivo do trabalho foi comparar duas metodologias para o zoneamento agricola de risco climatico da soja (Glycine max (L) Merrill) no Bioma Cerrado. Utilizou-se o Indice de Satisfacao da Necessidade de Agua (ISNA) considerando as fases fenologicas criticas ao deficit hidrico: Fase I (germinacao e emergencia) e Fase III (floracao e enchimento de graos). Na primeira abordagem considerou-se a fase III. Na segunda abordagem consideraram-se as fases I e III. Utilizou-se o programa SARRAZON para a simulacao do balanco hidrico. A zona de baixo risco climatico correspondeu ao ISNA > 0,50 na fase I; e, o ISNA> 0,65 na fase III. Para fins de comparacao considerou-se a epoca de semeadura, porcentagem das areas de risco e quantidade de municipios recomendados. Na segunda metodologia, as zonas de baixo risco foram menores. A soja foi recomendada em solos com maior capacidade de agua disponivel. As areas de alto risco situaram-se na transicao entre os biomas Caatinga e Pantanal. Esse estudo orienta o risco agroclimatico da soja e subsidia politicas publicas no Cerrado.Palavras-chave: agroclimatologia; gestao ambiental; politica agricola; planejamento ambiental. CLIMATIC RISK ZONING METHODOLOGIES FOR SOYBEAN CULTIVATION IN THE CERRADO BIOME ABSTRACT: Agriculture is an activity of risk and uncertainty. Agricultural Climate Risk Zoning (ZARC) indicates what, where and when to plant to escape climate events. The objective of this work was to compare two methodologies for agricultural climate risk zoning of soybean (Glycine max (L) Merrill) in the Cerrado Biome. The Water Requirement Satisfaction Index (WRSI) was used considering the phenological phases critical to water deficit: Phase I (germination and emergence) and Phase III (flowering and grain filling). In the first approach, phase III was considered. In the second approach, phases I and III were considered. The SARRAZON program was used to simulate water balance. The low climate risk zone corresponded to WRSI > 0.50 in phase I; and WRSI > 0.65 in phase III. For comparison purposes, the sowing time, percentage of risk areas and number of recommended municipalities were considered. In the second methodology, the low risk zones were smaller. Soybean has been recommended in soils with the highest available water capacity. The high-risk areas were in the transition between the Caatinga and Pantanal biomes. This study guides soy agroclimatic risk and subsidizes public policies in the Cerrado.Keywords: agroclimatology; environmental management; agricultural policy; environmental planning.