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Efficiency of nitrogen (15NH4)2SO4 utilization in triple intercrop of corn/palisade grass/pigeonpea and residual effect on lopsided oat pasture in crop livestock production system

Grant number: 14/21772-4
Support type:Scholarships in Brazil - Post-Doctorate
Effective date (Start): February 01, 2015
Effective date (End): January 31, 2018
Field of knowledge:Agronomical Sciences - Agronomy
Cooperation agreement: Coordination of Improvement of Higher Education Personnel (CAPES)
Principal Investigator:Carlos Alexandre Costa Crusciol
Grantee:Nídia Raquel Costa
Home Institution: Faculdade de Ciências Agronômicas (FCA). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

The research will be composed by two trials conducted in Botucatu-SP. The experimental design in the first trial will be randomized blocks with 24 replications, arranged in two modalities of corn cultivation for silage: intercropping with palisade grass {Urochloa brizantha (Hochst. ex A. Rich.) R. D. Webster var. Marandu [syn. Brachiaria brizantha (Hochst. ex A. Rich.) Stapf var. Marandu]} and intercropping with palisade grass and pigeonpea var. BRS Mandarim (Cajanus cajan), harvested 0.45 m above soil surface, ¼ milk grain stage (35% grain humidity). On the second trial will be used a subdivided parcels scheme. The treatments of the first trial will compose the parcels and the over sow lopsided oat var. EMBRAPA 29 (Garoa) (Avena strigosa) spread on or on rows subsequently harvesting for ensiling will compose sub parcels. The objective of the research will be to evaluate the dynamic and efficiency of N-fertilizer utilization on the soil-plant system in CLP system testing a triple intercrop of corn/palisade grass/pigeonpea for silage, and the effect on lopsided oat pasture over sown after harvesting and grazed by semi-confined lambs in the winter/spring. The N-fertilization with 15N, will be done on corn culture by occasion of nitrogen top-dressing fertilization, using 180 kg ha-1 N, utilizing enriched ammonium sulfate (15NH4)2SO4 having 3% isotopic abundance of 15N atoms. Therefore, the efficiency of N utilization in cultures established in the system will be evaluated, determining the percentage of N in plants derived from fertilizer (NPPF) and the quantity of N in plants derived from fertilizer (QNPPF) as the experiment is conducted. The percentage of 15N-fertilizer remaining in the soil will be determined as well by evaluating the total N in the layers of 0.0-0.20 e 0.20-0.40 m depths. The nutritional status and the corn plants fractions, forage yield for ensiling, dry mass and content of macronutrients in the stalks of corn remaining in the area will also be evaluated; as well as, the effect of lopsided oat over sown on: pasture dry mass yield; macronutrients content of forage straw; forage straw decomposition after desiccation in spring; changes of chemical and physical soil properties and soil carbon accumulation. The data will be submitted to analysis of variance by F test (p d 0.05). The straw decomposition will be adjusted by regression analysis and other results compared by t LSD test (p d 0.05). (AU)