Reduction of Nitrogen Fertilizer Requirements and Nitrous Oxide Emissions Using Legume Cover Crops in a No-Tillage Sorghum Production System

G. Y. Mahama, P. V. V. Prasad, K. L. Roozeboom, J. B. Nippert and C. W. Rice
Additional contact information
G. Y. Mahama: Department of Agronomy, 2004 Throckmorton Plant Science Center, Kansas State University, Manhattan, KS 66506, USA
P. V. V. Prasad: Department of Agronomy, 2004 Throckmorton Plant Science Center, Kansas State University, Manhattan, KS 66506, USA
K. L. Roozeboom: Department of Agronomy, 2004 Throckmorton Plant Science Center, Kansas State University, Manhattan, KS 66506, USA
J. B. Nippert: Division of Biology, 116 Ackert Hall, Kansas State University, Manhattan, KS 66506, USA
C. W. Rice: Department of Agronomy, 2004 Throckmorton Plant Science Center, Kansas State University, Manhattan, KS 66506, USA

Sustainability, 2020, vol. 12, issue 11, 1-18

Abstract: Nitrous oxide (N 2 O) emission from denitrification in agricultural soils often increases with nitrogen (N) fertilizer and soil nitrate (NO 3 − ) concentrations. Our hypothesis is that legume cover crops can improve efficiency of N fertilizer and can decrease N 2 O emissions compared to non–cover crop systems. The objectives of this study were to (a) evaluate the performance of summer leguminous cover crops in terms of N uptake and carbon (C) accumulation following winter wheat and (b) to quantify the effects of summer leguminous cover crops and N fertilizer rates on N 2 O emissions and grain yield of the subsequent grain sorghum crop. Field experiments were conducted in the context of a wheat-sorghum rotation for two seasons in Kansas. Treatments consisted of double-cropped leguminous cover crops following winter wheat harvest with no fertilizer applied to the following grain sorghum or no cover crop after wheat harvest and N fertilizer rates applied to the grain sorghum. The cover crops were cowpea ( Vigna unguiculata L. Walp.), pigeon pea ( Cajanus cajan L. Millsp.), and sunn hemp ( Crotalaria juncea L.). The three N treatments (were 0, 90, and 180 kg·N·ha −1 ). Fallow systems with 90 and 180 kg·N·ha −1 produced significantly greater N 2 O emissions compared with cropping systems that received no N fertilizer. Emissions of N 2 O were similar for various cover crops and fallow systems with 0 kg·N·ha −1 . Among cover crops, pigeon pea and cowpea had greater C accumulation and N uptake than sunn hemp. Grain yield of sorghum following different cover crops was similar and significantly higher than fallow systems with 0 kg·N·ha −1 . Although fallow systems with 90 and 180 kg·N·ha −1 produced maximum sorghum grain yields, N 2 O emissions per unit of grain yield decreased as the amount of N fertilizer was reduced. We conclude that including leguminous cover crops can decrease N fertilizer requirements for a subsequent sorghum crop, potentially reducing N 2 O emissions per unit grain yield and providing options for adaptation to and mitigation of climate change.

Keywords: crop rotation; cover crops; greenhouse gas emissions; legumes; nitrogen management; nitrous oxide; cropping system; sorghum (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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