Influence of Annual Compost Application on Soybean Productivity.

This research study was designed to evaluate the use of solid-separated compost (solids removed from liquid swine manure, composted with urban landscape waste) as a soil amendment for soybean (Glycine max) production. The entire experimental site (4 contiguous ha at Illinois State University Farm at Lexington, IL, USA) has uniform soil (Parr-Libson-Drummer Association). The 4.0 ha site has been split into two ‘blocks’ of 2.0 ha each. One block was planted into corn (Zea mays), and the other block into soybean to allow for a corn/soybean rotation between the blocks. Representative agronomic practices for most Illinois producers (except for compost) have been utilized for corn and soybean blocks at this experimental site. For the 2.0 ha block planted to soybean or corn, two 1.0 ha “plots” were established. One 1.0 ha plot was the “control” that did not receive solid-separated compost. The other 1.0 ha plot (“compost”) received solid-separated compost (supplied at 17.8 Mg/ha, on dry weight basis). Soil samples and plant tissue and productivity data were collected during the 2010, 2011, 2012, and 2013 growing seasons. Data were analyzed using a two sample t test (equal variance), with years considered as repeats. Preliminary results indicate that soybean yield was increased via the annual application of compost. The greater yield of the compost treatment could be due to an increase in plant dry weight, with concurrent increases in pod and seed number. The annual application of compost also increased soil P levels, as compared to the control. The ultimate impact of this study is to improve soybean yield and productivity in an environmentally sensitive and sustainable manner.