Fine-Tuning N Fertilization for Forage and Grain Production of Barley–Field Bean Intercropping in Mediterranean Environments

Silvia Pampana,Marco Mariotti,Victoria Andreuccetti,Iduna Arduini

doi:10.3390/agronomy12020418

Abstract

Optimizing the productivity and efficiency of cereal–legume intercropping through exploiting differences in nitrogen (N) acquisition of the two crops is crucial in Mediterranean areas. A two-year field study was conducted in Central Italy to determine how N fertilization rate affected forage and grain production as well as intercropping efficiency in a barley (Hordeum vulgare L.) and field bean (Vicia faba L. var minor) intercrop. Crops were grown as monocrops or intercropped in alternate rows in an additive design and fertilized with five N rates from 0 to 200 kg ha−1. Forage production was determined both at heading and early dough, while grain yield was assessed at full ripening. Besides, land equivalent ratio, competitive ratio, and aggressivity index were calculated. Consistently between years, results highlighted that intercropping of barley with field bean can be a sustainable cropping system because both forage production and efficiency indices improved. Anyway, with 150 and 200 kg N ha−1, the grain yield was lower in intercropping than in sole crops, due to higher interspecific competition. We concluded that the optimal N fertilization depends on the farmer’s objective in terms of forage or grain production and the targeted proportion between the cereal and the legume at harvest.

Highlights

The goal of sustainable agriculture is to concurrently deliver several services such as providing food security, maintaining natural resources, retaining and improving farmers’ profitability, and sustaining biodiversity [1,2].Sustainable alternatives are directly or indirectly designed to increase the diversity of cultivated crops [3]
One of the most frequent strategies for diversification of cropping systems is to substitute agrochemicals and fossil fuels with the ecosystem services provided by legumes, as they have the unique ability to establish a symbiosis with rhizobia to fix atmospheric N2 [4,5]
The dominant species may display a slighter decrease in the harvest index than the subordinate species, according to [68,69]. This is in line with our results, as we found that the grain of field bean in the intercropping was reduced to the aerial biomass, and Harvest index (HI) was not significantly changed

Summary

Introduction

The goal of sustainable agriculture is to concurrently deliver several services such as providing food security, maintaining natural resources (i.e., soil, energy, and water), retaining and improving farmers’ profitability, and sustaining biodiversity [1,2].Sustainable alternatives are directly or indirectly designed to increase the diversity of cultivated crops [3]. Intercrops, and markedly with legumes, may warrant the diversification of agricultural systems by concurrently increasing the number of cultivated species and comprising a larger proportion of legumes in rotations [8,9,10]. This often determines increased productivity and land use efficiency, together with several ecosystem services, such as improving adaptability of production to climate change and potentially allowing a greater resilience to biotic and abiotic stresses [11,12,13,14,15]

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Discussion

Conclusion