Controlling Soil Ecosystem Services Via Soil Cover in Orchards.

It is well known that the selection of a given practice in agriculture has key impacts on the ecosystem services that the agricultural soils can provide. In particular, an intensive agriculture with bare soil promotes soil degradation processes as a result of increased level of runoff and soil erosion, caused by the raindrop impact on the bare soil.  The intensive runoff and soil erosion induce negative processes such as soil fertility loss; leaching of pesticides, herbicides and nutrients from the agriculture land to the nearby ecosystems; increased flooding risks due to a decrease in the transmission capacity of streams to overlade of sediments, and more.

Here we present the results of a three years study on the magnitude and values that can be provided by alternative agricultural practices. In our field study we examined the consequences of covering citrus orchards' floor with woodchips below trees and annual winter cover crops between rows. We found that inter-cropping reduced the runoff maximum discharge by 60-80%, reduced the cumulative runoff by 70-90%, and decreased soil erosion and runoff by 95%. Moreover, using native vegetation as proxy of cover crops between the rows, we were able to increase both the herbs and arthropods biodiversity, and maintain the development and heath of the orchard trees. The biodiversity includes endemic herbs species and predators and parasites of pests. The effect of using cover crops in citrus orchards on biological control was inconclusive at this point. Whereas pests were somewhat more abundant on the foliage in the presence of cover crops, natural resistance to pest outbreaks might be higher when cover crops are present as a result of greater diversity of natural enemies.

Our study strength the need to develop integrated best management practices for sustainable citrus orchards, while taking into consideration the following key features: agronomic achievements (tree performance, quantity and quality of crop yield); disease and pest control; water use efficiency; conservation of genetic biodiversity;  soils regulatory services (prevent runoff, sediment transportation, river pollution and blockage). The value of the overall benefits from the developed agricultural practices is economically quantified at $$ annually added value, per hectare.