Cover Crop Selection by Jointly Optimizing Biomass Productivity, Biological Nitrogen Fixation, and Transpiration Efficiency: Application to Two Crotalaria Species

Verónica Berriel,Carlos H Perdomo,Jorge Monza

doi:10.3390/agronomy10081116

Verónica Berriel, Carlos H Perdomo + Show 1 more

Open Access

https://doi.org/10.3390/agronomy10081116

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Journal: Agronomy	Publication Date: Aug 1, 2020
Citations: 12	License type: CC BY 4.0

Affiliation: Universidad de la República

Abstract

Crotalaria spectabilis and Crotalaria juncea are cover crops (CC) that are used in many different regions. Among the main attributes of these species are their high potential for biomass production and biological fixation of nitrogen (BNF). Attempting to maximize these attributes, while minimizing water consumption through high transpiration efficiency (TE), is a challenge in the design of sustainable agricultural rotations. In this study, the relationship between biomass productivity, BNF, and TE in C. spectabilis and C. juncea was evaluated. For this purpose, an experiment was carried out under controlled conditions without water limitations and using non-inoculated soil. BNF was determined by the natural abundance of 15N, while TE was estimated by several different methods, such as gravimetric or isotopic method (13C). C. juncea produced 42% less dry matter, fixed 28% less nitrogen from the air, and had 20% less TE than C. spectabilis. TE results in both species were consistent across methodologies. Under simulated environmental conditions of high temperature and non-limiting soil water content, C. spectabilis was a relatively more promising species than C. juncea to be used as CC.

Highlights

The use of legumes as cover crops (CC) in agricultural rotations makes it possible to reduce the production costs associated with a lower use of nitrogenous fertilizers, which results in environmental benefits [1,2]
The foliar N concentration was positively correlated with transpiration efficiency (TE) and intrinsic WUE (iWUE) (Table 4)
The results indicate that C. spectabilis is more promising than C. juncea for use as a CC in this relatively high A/g ratios

Summary

Introduction

The use of legumes as cover crops (CC) in agricultural rotations makes it possible to reduce the production costs associated with a lower use of nitrogenous fertilizers, which results in environmental benefits [1,2]. CCs are used to reduce soil erosion caused by high precipitation, minimize surface runoff, and provide channels to the subsurface layers of the soil, allowing an increased infiltration rate [3,4]. Some of the main attributes of these species are their rapid and high productivity of biomass (8 Mg ha−1 ) [6,7,8] and their high content of foliar nitrogen, obtained by biological nitrogen fixation (BNF) at an average of 150 kg N ha−1 [9,10,11]. The biomass production of CCs, including C. juncea and C. spectabilis, is positively correlated with the recycling of nutrients, the entry of carbon (C) into the soil [13,14,15], and a decrease in the rate of erosion [3].

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