Estimation of soil coverage of chopped pruning residues in olive orchards by image analysis

Abstract

Residue chopping from orchard pruning is becoming a common practice in conservation agriculture after the establishment of eco-conditionality policies in the European Union. This type of residue is used to protect the soil from erosion and improve the water balance and fertility of soils by improving the organic matter content. However, no studies have evaluated the influence of pruning residues and size on soil coverage. This study examines the effect of different treatments on pruning residue soil coverage in an olive orchard (cv. Picual). Treatments consisted of two quantities of pruning residues, specifically, high (2.04 kg m-2) and low (1.02 kg m-2), and two chopping speeds, low (2.4 km h-1) and high (3.2 km h-1). The different treatments were evaluated by image analysis and pixel counting to determine the soil cover percentage, size, number and distribution of the pruning residues after chopping. After chopping, the soil cover percentage was 39% higher in the high quantity pruning residue treatments but was not significantly influenced by the chopping speed. The size and number of lignified residues was quantified via pixel counting. In the high quantity pruning residue treatments, the number of large lignified residues (> 6 cm2) was higher, and the number of pruning residues smaller than 2 cm2 was lower, when compared with low quantity pruning residue treatments. The high chopping speed treatments produced more smaller-sized pruning residues.