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Agricultural soil quality is an issue that has been widely debated in the literature in recent decades. Three olive grove areas (one in Lisbon and the others in Santarém, Portugal) with different management techniques (intensive and super-intensive) were selected. Nutrient concentrations and enzyme activities of soils were determined, as well as the C and N of litter and pruning waste (mulch) to estimate the influence of management techniques on the quality of olive grove soils and to assess the extent to which they are affected by organic covers and different cultivation intensities. Organic C and total N concentrations in soils of the intensive olive grove in Lisbon were the highest when compared with those in the intensive and super-intensive olive groves soils of Santarém. The concentrations of Ca, Mg, Na, and K were the main differences between the Lisbon olive groves and the other two from Santarém. Phosphatase, cellulase, and urease activities were related to the Na, extractable K, extractable P, Zn, Mn, organic C, and total N soil concentrations. Soil management and agricultural practices are determining factors for these enzymatic activities of Santarém olive groves, although climate conditions and soil properties play an important role in the soil enzymatic activities. [ABSTRACT FROM AUTHOR]

In this study, avocados of the Hass variety cultivated in Almuñécar (Granada, Spain) are analyzed after soil mulching with pruning debris. The mulch treatment assay was composed of pruning wastes from subtropical crops (avocado, cherimoya, and mango) and garden wastes from the surrounding areas. The aim of this work is to analyze the nutrient content in avocado fruit and the effect of pruning-waste mulching on fruit development over four years. Avocado fruits collected in 2013, 2016, and 2017 were weighed, their volume and their sugar content were calculated, and macro- and micronutrients were analyzed in the peel, pulp, and stone (endocarp and seed). The pulp contained the highest concentration of nutrients, especially Cu, Zn, P, Na, and Ca. The peel presented high concentrations of Mn, K, and N, while the stone recorded the lowest values in nutrients, with the greatest decreases in years with the lowest precipitations registered. Over the study period, a decline was detected in the nutrient concentrations related to the alternation of high and low yields, typical of this crop, due to environmental factors. In the years 2016 and 2017, avocados accumulated higher amounts of micronutrients and P, presumably because of greater water availability in the soil. During the study period, the application of pruning wastes did not affect the nutrient concentration of fruits except for the garden pruning waste in certain elements in the pulp during the last study year. [ABSTRACT FROM AUTHOR]

A field experiment was conducted on the Andalusian coast (Granada, Southern Spain) to study the time course of nutrient release into the soil after the addition of bagged pruning waste from subtropical orchard trees (avocado, cherimoya, and mango) and urban garden waste over three two-year periods. N, P, and K concentrations were greater in the garden waste, whilst avocado and cherimoya pruning waste registered the highest values for Mg. In general, micronutrient contents were low in all waste, especially Cu. Macronutrient release followed a three-phase dynamic: fast initial release, intermediate stabilization, and final increase. Garden waste showed a similar time course in all three trees and released greater concentrations of K and P. The annual decomposition rate factor k was negative for N and Ca in the avocado tree, indicating strong biological activity in this plot. Avocado, cherimoya, and garden waste showed a good microbial degradation, improving soil quality by increasing carbon and nitrogen contents as well as soil microbial activity. As for the mango tree, its special microclimatic conditions appeared to favor waste photodegradation, thus eliminating nutrients that were not incorporated into the soil. Soil enzymatic activities increased in the avocado and cherimoya trees with the addition of all waste. In the mango tree, only an increase in urease was detected after the addition of garden waste. Our results suggest that the time course of organic waste in different subtropical trees grown on similar soils is significantly conditioned by the microclimatic characteristics. [ABSTRACT FROM AUTHOR]