Nitrogen Yields and Biological Nitrogen Fixation of Winter Grain Legumes

Reinhard W Neugschwandtner,Agnieszka Klimek-Kopyra,Kuanysh K Zholamanov,Hans-Peter Kaul,Alexander Bernhuber,Helmut Wagentristl,Tomáš Lošák,Stefan Kammlander

doi:10.3390/agronomy11040681

Abstract

Grain legumes are valuable sources of protein and contribute to the diversification and sustainability of agricultural systems. Shifting the sowing date from spring to autumn is a strategy to address low yields of spring grain legumes under conditions of climate change. A two-year field experiment was conducted under Pannonian climate conditions in eastern Austria to assess the nitrogen yield and biological N2 fixation of winter peas and winter faba beans compared to their spring forms. The grain nitrogen yields of winter peas and winter faba beans were 1.83-fold and 1.35-fold higher compared to their spring forms, respectively, with a higher value for winter peas. This was mainly due to higher grain yields of winter legumes, as winter faba beans had a 1.06-fold higher grain nitrogen concentration than spring faba bean. Soil mineral nitrate after harvest was similar for all grain legumes, with by 2.85- and 2.92-fold higher values for peas and faba beans than for cereals, respectively. The N2 fixation of winter peas and winter faba beans were 3.90-fold and 2.28-fold higher compared to their spring forms, with winter peas having a 1.60-fold higher N2 fixation than winter faba beans. The negative nitrogen balance of winter peas was smaller than that of winter faba beans as they demonstrated the ability to overcompensate for higher nitrogen removal with grain through higher N2 fixation. The cultivation of winter grain legumes, especially winter peas, can be recommended under Pannonian climate conditions as they achieve high nitrogen yields and high levels of N2 fixation.

Highlights

Grain legumes, such as pea (Pisum sativum L.) and faba bean (Vicia faba L.), are valuable sources of protein and energy for animals; they have been discussed as an alternative to soybean meal [1]
A two-year field experiment was conducted under Pannonian climate conditions in eastern Austria to assess the nitrogen yield and biological N2 fixation of winter peas and winter faba beans compared to their spring forms
The grain nitrogen yields of winter peas and winter faba beans were 1.83-fold and 1.35-fold higher compared to their spring forms, respectively, with a higher value for winter peas. This was mainly due to higher grain yields of winter legumes, as winter faba beans had a 1.06-fold higher grain nitrogen concentration than spring faba bean

Summary

Introduction

Grain legumes, such as pea (Pisum sativum L.) and faba bean (Vicia faba L.), are valuable sources of protein and energy for animals; they have been discussed as an alternative to soybean meal [1]. There is a great deficit of about 70% of high-protein feed for livestock in Europe, which is met by imported soybean and soymeal [2]. To reduce this deficit, grain legume production in Europe has to be increased, e.g., by introducing more drought resistant grain legume species, such as chickpea [3], and by using winter grain legumes [4,5]. Grain legumes contribute to the diversification and long-term productivity of sustainable agricultural systems as they can satisfy the bulk of their nitrogen (N) demand from atmospheric nitrogen through symbiosis with nitrogen fixing soil bacteria (Rhizobium spp.), thereby minimizing the demand for N fertilizer inputs within crop rotations [6]. Agronomic management offers opportunities for increased NFIX, e.g., by supporting higher yields through irrigation, phosphate and sulfur fertilization, liming for optimal soil pH, weed control, reducing row spacing and optimizing plant density or sowing dates [8,9,10]

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