Effect of the implementation of alley crops on the soil physical properties of a mandarin crop with regulated irrigation deficit, in the Mediterranean region

Abstract

In the Mediterranean region, orchard aisles usually remain bare throughout the year, which causes soil degradation and erosion. Alley cropping could be a suitable strategy to improve soil physical quality while increasing land productivity. The aim of this study was to assess if alley cropping in a mandarin orchard can affect water content at field capacity, wilting point, available water, aggregates stability, bulk density, and saturated hydraulic conductivity and if there is a relationship between these and crop production and quality. For this, three different treatments were applied: i) a mandarin monoculture (MM); ii) a mandarin crop diversified with a multiple cropping of vetch/barley and fava bean (AC1), with regulated deficit irrigation (RDI); and iii) a mandarin crop diversified with a rotation of fava bean, purslane and cowpea, with RDI (AC2). After three crop cycles, we found an increase in the amount of available water in all treatments, being slightly higher in AC2. The mean weight diameter of soil aggregates was reduced in all treatments, especially in AC1 (> 45 %). Saturated hydraulic conductivity increased in all treatments, especially in MM. In addition, we observed an increase in moisture at field capacity and available water results in larger mandarins, with a lower proportion of soluble solids. Thus, the establishment of alley crops did not lead to a better evolution of the soil physical properties in the short-term. However, the effect of diversification systems on the soil physical properties would be appreciated with the establishment of the mandarin crop diversified with cover crops or perennial crops in a long-term period.