Influence of Recycled Waste Compost on Soil Food Webs, Nutrient Cycling and Tree Growth in a Young Almond Orchard

Amanda K Hodson,Maria C C P Lyra,Jordan M Sayre,Jorge L Mazza Rodrigues

doi:10.3390/agronomy11091745

Amanda K Hodson, Maria C C P Lyra + Show 2 more

Open Access

https://doi.org/10.3390/agronomy11091745

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Abstract

Composting is an effective strategy to process agricultural and urban waste into forms that may be beneficial to crops. The objectives of this orchard field study were to characterize how a dairy manure compost and a food waste compost influenced: (1) soil nitrogen and carbon pools, (2) bacterial and nematode soil food webs and (3) tree growth and leaf N. The effects of composts were compared with fertilized and unfertilized control plots over two years in a newly planted almond orchard. Both dairy manure compost and food waste compost increased soil organic matter pools, as well as soil nitrate and ammonium at certain time points. Both composts also distinctly altered bacterial communities after application, specifically those groups with carbon degrading potential, and increased populations of bacterial feeding nematodes, although in different timeframes. Unique correlations were observed between nematode and bacterial groups within compost treatments that were not present in controls. Food waste compost increased trunk diameters compared to controls and had greater relative abundance of herbivorous root tip feeding nematodes. Results suggest that recycled waste composts contribute to biologically based nitrogen cycling and can increase tree growth, mainly within the first year after application.

Highlights

Soil health has been defined as “the capacity of the soil to function as a vital living ecosystem that supports plants, animals, and humans” [1]
The current study examined the effects of applying two recycled waste composts in an almond orchard, comparing them to either a fertilized (N+) or unfertilized (N−) control over two years
After compost application in May of year one, food waste compost (FWC) treated plots had higher NH4+-N than controls (p < 0.01) and a similar trend was observed for dairy manure compost (DMC) (p = 0.06)

Summary

Introduction

Soil health has been defined as “the capacity of the soil to function as a vital living ecosystem that supports plants, animals, and humans” [1]. Composting can transform agricultural and municipal waste into a valuable soil amendment which increases SOC [7,8], while at the same time increasing soil nutrients and yields [9,10] Both dairy manure [11] and food waste [12,13] have negative environmental effects, and composting offers one solution to recycle these wastes. Dairy manure compost applied at a rate of 105 Mg DM ha−1 increased SOC by 73% and supported corn yields similar to that of inorganic fertilizer [14] In wheat, both municipal organic waste compost [9] and dairy manure compost [15] increased soil nutrient pools and yield. Recycled waste composts can increase SOC in almond production [16] and are applied by growers with the goals of increasing tree nutrition and beneficial soil biology [17]

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