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Nitrogen destination applied to the maize crop and its effect on soybeans next cultivated

Grant number: 18/15867-3
Support type:Scholarships in Brazil - Doctorate
Effective date (Start): December 01, 2018
Effective date (End): February 28, 2021
Field of knowledge:Agronomical Sciences - Agronomy - Soil Science
Principal Investigator:Ciro Antonio Rosolem
Grantee:Bruno Gazola
Home Institution: Faculdade de Ciências Agronômicas (FCA). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
Associated research grant:15/50305-8 - A virtual joint centre to deliver enhanced nitrogen use efficiency via an integrated soil-plant systems approach for the UK & Brazil, AP.TEM

Abstract

Some forages of the genus Urochloa can inhibit the process of nitrification in the soil. As a consequence, N losses of the soil-plant system can be reduced by leaching and denitrification and the maintenance of mineral N in the form of ammonium (NH4 +) may favor the absorption of the nutrient by maize (Zea mays L.). When safflower maize is grown in rotation with soybeans, although soybean [Glycine max (L.) Merrill] may respond to N applied to corn, this is not demonstrated, and it is not known whether it is a response to applied N or to improvement of the system. The objective of this study was to study whether the cultivation of tropical forage in consortium with maize reduces nitrification in the soil and increases the recovery of 15N-fertilizer by maize (second harvest) and its residual by soybean (harvest). An experiment will be carried out under field conditions from 2018 to 2021. The treatments will be a control without forages, cultivation of Brachiaria ruziziensis (U. ruziziensis) and Tanzania grass (Megathyrsus maximum), and N doses applied in maize (0, 80, 160 and 240 kg ha-1 N). The forages will be cultivated for seven months, with subsequent sowing of soybeans, followed by corn, in the 2018/2019 harvest. In the following harvests, the rotation sequence will be soybeans, corn being cultivated in consortium with forage species. The production of biomass and accumulation of N by the crops will be evaluated, as well as the recovery of 15N-fertilizer. Emissions of ammonia and nitrous oxide in addition to nitrate leaching will be evaluated throughout the experiment. The crude ammonification and nitrification rate and real-time PCR (qPCR) of genes will also be determined to unravel the effect of forages on the N cycle in the soil. The data collected will be submitted to ANOVA and the means separated by Fisher's LSD test (P d 0.05). (AU)