Macronutrients released during the decomposition of pruning residues used as plant cover and their effect on soil fertility

Abstract

SUMMARYThe arrival on the market of various types of mulchers and chippers has boosted the use of pruning residues as plant cover among olive growers. In order to increase knowledge regarding the decomposition of these types of residues and their effect on soil fertility, an experiment was performed using different doses and sizes of pruning residues applied on the areas between the lines of olive trees in an organic olive grove.Experiments were conducted over a period of two growing seasons (2009/10 and 2010/11). Treatments consisted of fine (⩽8 cm in diameter) and thick (>8 cm in diameter) pruning residues in the amounts indicated, I=2·65 kg/m2 fine; II=2·65 kg/m2 fine+1·12 kg/m2 thick; III=5·30 kg/m2 fine; IV=5·30 kg/m2 fine+2·24 kg/m2 thick; and a control without residues.As regards the loss of biomass and nutrients during the decomposition of residues, two phases were observed. First, soluble compounds were degraded during a rapid initial phase, while in a second and slower phase, lignocellulosic compounds were decomposed. As a result, the pattern over time of nitrogen (N), phosphorus (P) and potassium (K) release fitted a double exponential model better, regardless of the treatment considered, registering in most cases determination coefficients close to one.The favourable results observed in terms of augmentation in N, P and K soil content following the application of pruning residues confirmed a greater improvement in soil fertility than the soil covered by spontaneous weeds, which is the option most frequently adopted by organic olive growers. The initial amount of pruning residues has influenced the amount of soil nutrients. Considering the entirety of the soil profile (0–40 cm) and the content of these elements in the soil, treatment III, which contained the largest amount of fine residues, was the most efficient in terms of improving soil fertility, recording increases in the concentration of N, P and K of 1805·4, 53·1 and 598·7 kg/ha, respectively. The most unfavourable results were recorded by treatment I, with increases of 480·9 kg/ha in the case of N and a decrease in P content with regard to the control sample. Treatment II increased K (recording 215·2 kg/ha) which was the least in comparison to the control sample.

Decomposition and nutrient mineralisation of leaf litter in smallholder cocoa agroforests: a comparison of organic and conventional farms in Ghana

“…For example, non-structural elements such as K are rapidly lost from the organic material when the cell wall breaks down during decomposition and soluble P containing compounds are easily leached during decomposition compared to N which participates in the structural section of organic compounds; hence, it is slowly released during decomposition (Issac and Nair 2005;Hossain et al 2011;Dawoe et al 2010;Naik et al 2018). Ordóñez-Fernández et al (2015) indicated that K is highly soluble and mobile, that implies environmental conditions such as soil moisture or rainfall may possibly accelerate its release from decomposing matter compared to other nutrients. Additionally, preferential retention of N by microbes while K or P is being rapidly released from the substrate may account for the faster release of P and K than N (Singh and Sherhar 1989).…”

Study of C, N, P and K Release from Residues of Newly Proposed Cover Crops in a Spanish Olive Grove

“…Nevertheless, most olive growers use spontaneous vegetation due to economic savings in seed. In 2018, 92% of the Spanish olive grove areas with any type of CC had a spontaneous CC [16] that was occasionally combined with mulch cover of pruning residues, which are durable, protect the soil and enhance soil fertility [17][18][19][20]. However, the continued use of the same CC produces a change in ruderal flora.…”

Assessing Local Uncertainty of Soil Protection in an Olive Grove Area with Pruning Residues Cover: A Geostatistical Cosimulation Approach

“…Furthermore, Parras‐Alcántara et al () also observed that pruning residues used as a mulch can improve soil physical and chemical properties in olive groves. Likewise, Ordóñez‐Fernández et al () found an increase in the soil contents of N, P and K following the application of this kind of residues. Indeed, farmers are increasingly adopting chopped pruning as mulch (Calatrava & Franco, ).…”

“…The decomposition of pruning residues is a complex process (Ordóñez-Fernández et al, 2015). The size of the remains affects the specific surface in contact with the ground and therefore its microbial colonization.…”