Fate of N-15 fertilizer applied to maize in rotation with tropical forage grasses

Author(s)

Rocha, Kassiano F. ^[1] ; Mariano, Eduardo ^[1] ; Grassmann, Camila S. ^[1] ; Trivelin, Paulo C. O. ^[2] ; Rosolem, Ciro A. ^[1]

Affiliation

^[1] Sao Paulo State Univ, Coll Agr Sci, Av Univ 3780, BR-18610034 Botucatu, SP - Brazil

^[2] Univ Sao Paulo, Ctr Nucl Energy Agr, Lab Stable Isotopes, Piracicaba, SP - Brazil

• Document type: Journal article
• Source: FIELD CROPS RESEARCH; v. 238, p. 35-44, MAY 15 2019.
• Web of Science Citations: 1

Abstract

Tropical forage grasses of the genus Megathyrsus and Urochloa can suppress soil-nitrification by releasing inhibitory substances, reducing N losses and increasing fertilizer N recovery of the cash crop in rotation. In contrast, ruzigrass (Urochloa ruziziensis) has been reported to decrease the yield and N accumulation of the subsequent crop and hence can affect N use efficiency and the fate of applied N. We investigated the effects of Guinea grass (M. maximum), palisade grass (U. brizantha), and ruzigrass on succeeding crop yield, N accumulation, and the fate of N-15-labeled fertilizer applied to maize (Zea mays L.) in a 2-year field experiment in Brazil. Maize was fertilized with 140 kg ha(-1) N as ((NH4)-N-15)(2)SO4 or not fertilized, and recovery of residual N-15 was quantified in the second season. Net nitrification rates through an incubation study had no differences among grasses. Nitrogen application increased maize yield and N accumulation in both seasons, whereas maize yield decreased by 9.5% following ruzigrass compared with the other forages. The grasses had no effect on N-15 recovery by maize or in the system. On average, the recovery of N-15 in maize and soil was 34% and 46% in the first growing season and 2.9% and 20% in the second season, respectively. Our results indicated that tropical perennial grasses had no differential effects on nitrification rates and the fate of N-15-labeled fertilizer in the plant-litter-soil system in the season of application nor in the subsequent crop (residual effect). (AU)

• FAPESP's process: 15/50305-8 - A virtual joint centre to deliver enhanced nitrogen use efficiency via an integrated soil-plant systems approach for the UK & Brazil
• Grantee: Ciro Antonio Rosolem
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 16/25253-7 - Nitrogen dynamics in a cropping system with forages as cover crops and corn
• Grantee: Camila da Silva Grassmann
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• FAPESP's process: 17/02517-1 - Nitrogen dynamics in a production system using Brachiaria as a cover plant
• Grantee: Eduardo Mariano
• Support Opportunities: Scholarships in Brazil - Post-Doctoral