Earthworm Inoculation Improves Upland Rice Crop Yield and Other Agrosystem Services in Madagascar

Abstract

The effects of earthworm inoculation and cropping systems on upland rice systems were examined over a four-year period in the Highlands of Madagascar. Each year, endogeic earthworms Pontoscolex corethrurus (Rhinodrilidae) were inoculated (EW+) at a density of 75 ind m−2 or were not inoculated (EW0). Inoculation was tested in three cropping systems: conservation agriculture (CA) and traditional tillage with or without residues restitution. Soil and plant properties were measured during the first three years while soil biological properties were assessed at the fourth year. At the end of the experiment, earthworm density was three-fold higher in EW+ than in EW0, demonstrating the success of the inoculation. Earthworm density was more important in CA than in tillage systems. Earthworm inoculation had higher significant effects on soil and plant properties than cropping systems. Earthworm inoculation had positive effects on soil macroaggregation (+43%), aboveground biomass (+27%), rice grain yield (+45%), and N grain amount (+43%). Intensifying earthworm activity in field conditions to meet the challenge of ecological transition is supported by our study.

A Symbiotic System of Irrigated Rice–Earthworm Improves Soil Properties and Rice Growth in Southern China

“…Numerous previous studies have shown that earthworm inoculation increases the yield of spinach [43], peanut [44], upland rice [26], rainfed rice [27,28] and other crops. However, only Liang et al confirmed the effect of earthworm inoculation on irrigated rice yield increasing through the rice ridge planting experiment [29].…”

“…Studies have shown that inoculation of earthworms in dryland ecosystems can improve physical properties [11,12], chemical properties [13,14] and biological properties [15,16] of soil, accelerate the decomposition of soil pollutants [17], reduce heavy metal activity [18] and promote crop growth [19][20][21]. However, studies on the symbiotic relationship between earthworms and rice are mainly concentrated in the laboratory [22,23], upland paddy fields [24][25][26] or rainfed paddy fields [27,28]; studies under irrigated paddy fields are scarce with the exception of Liang et al [29]. The biggest technical difficulty is that the traditionally irrigated paddy environment during rice planting is not suitable for the growth of earthworms.…”