Use of Temporary Grass Component and Compost to Improve Soil Quality in an Organic Rotation.

A temporary grass component within an organic crop rotation may be capable of improving soil quality. The objective of this research was to evaluate soil quality changes in two different rotations: with and without grass and at two rates of manure application. Variables measured were bulk density (BD), wet/dry aggregate stability (WA&DA GMD), saturated hydraulic conductivity(K_sat), and soil nutrients(SOM, N, P, K, Ca, Mg, and Zn).

The research was conducted on a rotation experiment at the WVU Organic Farm in Morgantown, WV. Two rotations were studied, four and seven year durations, with the same crop sequence (corn, soy, wheat, kale), and three years of orchard-grass/red clover added to the 7-year rotation. Two bi-annual manure rates (Low (L):0 and High (H):22.5Mg/ha) were applied. Analysis of variance (ANOVA) was performed on the data.

For the year 2014, results indicated statistically significant soil property changes between first and last year of grass (e.g. BD from 1.18g/cm³ to 1.23g/cm³; SOM from 34.0g/kg to 39.6g/kg). Seven-yr plots had significantly higher surface (0-5cm) fertility (e.g. P=54.2ppm, K=164.6ppm, pH=5.6) than 5-yr plots(e.g. P=32.0ppm, K=136.3ppm, pH=5.51).

A significant effect of the grass component was observed on the rotation soil properties between the first (corn) and last (kale) crop sequence. In the 7-yr corn, BD (1.13g/cm³) and SOM(37.35g/kg) were significantly different from corn in the 4-yr rotation BD(1.17g/cm³) and SOM(35.06g/kg). In the 7-yr kale, SOM(35.1g/kg) was significantly higher than kale in the 4-yr rotation(SOM=31.07g/kg). Plots in the 7-yr corn had significantly different surface (0-5cm) fertility(e.g. P=72.8ppm, K=188ppm, pH=5.63) than plots in the 4-yr corn(e.g. P=86.8ppm, K=186ppm, pH=5.4). Plots in the 7-yr kale had significantly different surface fertility(e.g. P=24.5ppm, K=125.8ppm, pH=5.44) than plots in the 4-yr kale (e.g. P=29.6ppm, K=125.5ppm, pH=5.37).

This research may increase the understanding of the effect of a grass component within organic rotations on soil quality.