Effects of a compost application on soil properties in an intensive olive grove (var. Galega vulgar)

Abstract

Composting organic by-products of agricultural origin increases the value of waste which, without further use, can be an environmental, economic and social problem. A trial of compost application in an intensive olive grove (var. “Galega vulgar”) in Monforte is presented, with the aim of evaluating short-term effects (14 months) on physical and chemical characteristics of the soil. The compost incorporated, in equal proportions: (i) leaves and branches from olive cleaning, (ii) sheep manure and (iii) extracted olive pomace. In a randomized block experiment (3 treatments, 4 replications, 12 plots), the following doses were applied to the line: T0 = 0, T1 = 2.5 and T2 = 5.0 kg m^-2. Determinations included soil bulk density (0-5 cm), organic C, total N, C/N ratio, extractable P2O5 and K2O, extractable Fe, Mn, Cu and Zn (0-5, 5-15 and 15-30 cm). After 14 months, there were the following significant differences in relation to T0, especially in the 0-5 cm layer: lower soil bulk density (higher porosity) in T2; higher organic C and total N (T2); higher pH_H2O and pH_KCl (T1 and T2); lower Mn content (T2) and higher Zn content (T1 and T2). There is an improvement in soil health, but Zn monitoring is recommended if this compost is applied regularly.