Earthworms and litter management contributions to ecosystem services in a tropical agroforestry system

Abstract

Issues of food security, environmental degradation and global climate change underscore the need for the improved understanding of sustainable agricultural systems around the globe. The Quesungual slash-andmulch agroforestry system (QSMAS) of western Honduras offers a promising alternative to traditional slashand-burn (SB) agriculture for the mountainous tropical dry forest zones of Central America, but the overall influence of this system on soils is not fully understood. We examined earthworm populations, soil fertility and soil organic matter (SOM) dynamics under QSMAS and SB agriculture, with secondary forest (SF) as a reference. Both QSMAS and SB consisted of treatments with and without inorganic fertilizer (N-P-K) additions, resulting in five management treatments, each present on three replicate farms. ; respectively). Significant interactions between cropping system and fertilization suggest that QSMAS increased the availability of added inorganic P, 3 times more under QSMAS than for SB. Comparisons with SF, indicated that both cropping systems resulted in a dramatic loss of C (average 5 g C kg − 1 soil) since treatment implementation, and that this loss was mainly associated with the disruption of C rich large macroaggregates (> 2000 µm). After taking into account baseline soil C differences between plots, no major differences in total SOM losses were found between QSMAS and SB management. However, earlier establishment of QSMAS plots suggests that the overall rate of C loss since treatment establishment was lower for QSMAS than for SB. Results from this study suggest that the Quesungual agroforestry system offers great potential to improve soil fertility and biological health in the region relative to traditional slash-andburn agriculture.

Earthworms Building Up Soil Microbiota, a Review

“…The reduction of microbial immobilisation has been suggested as another driver of enhanced N mineralisation by earthworms, which may ultimately lead to an increase in NO − 3 -N leaching (Domínguez et al, 2004). Some authors, however, did not detect any earthworm effect on potentially mineralisable N (Fonte and Six, 2010) or, on the contrary, evidenced a decrease in N mineralisation by earthworms (Groffman et al, 2015), most likely due to an increase in microbial immobilisation that caused total soil N to decrease by 90 g N m −2 in presence of the epigeic L. rubellus. A possible explanation which has been proposed by several authors is that N mineralised by earthworms and their associated microorganisms might be used more readily by plants, thereby masking an increase in soil available N concentrations (Pashanasi et al, 1996;González and Zou, 1999;Wu et al, 2017).…”

Land use as a driver of soil fertility and biodiversity across an agricultural landscape in the Central Peruvian Andes

“…Cropped fields and pastures in the low-mid elevation zone generally presented the highest macrofauna abundance with high densities of earthworms and beetles (Table 3). Given their role as ecosystem engineers, earthworms are of particular relevance due to their large potential impacts on plant growth, soil structure, and organic matter dynamics (Lavelle et al 1997, Fonte andSix 2010). Earthworms are likely to benefit from the high productivity and associated inputs of organic matter in these systems, both as manure and as plant roots (Ernst andEmmerling 2009, Fonte et al 2009).…”

Role of Earthworm in Improving Soil Structure and Functioning

“…A decline in organic matter from an arable land with high earthworm population was recorded after 15 years 31 . It appears that earthworms can stabilize the soil organic matter when organic residues are regularly added to the soil 32 . Addition of organic matter is recommended rather than the inoculation of earthworms into the soil alone, to improve the soil fertility in the agro-ecosystem 33 .…”