Farm management and soil quality : an investigation into the effects of conventional and organic crop rotation systems on soil quality indicators : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Agricultural Science in Soil Science at Massey University
The physical and biological properties of soil from the pasture phase of organic and conventional crop rotation systems were compared. At the same time, a similar comparison was made of soil from the crop phase versus soil of the pasture phase of organic plots. A search was started for a new biological indicator of soil quality. The potential use of the relative abundance of fluorescent pseudomonad bacteria in rhizosphere soil and on the rhizoplane of plants in conventional and organic plots was explored. Soil respiration was also evaluated as an indicator of soil quality. Several soil amendments including earthworm casts, rhizosphere soil, compost material and biodynamic "preparation 500" were examined for their effect. The research has concluded that; 1. The pasture phase of organic crop rotation had superior soil quality to the similar pasture phase of the conventional plot. 2. Though recently cultivated, the pasture phase of the organic rotation system was able to restore appropriate levels of soil quality. 3. The relative abundance of fluorescent soil pseudomonad bacteria was greater in soil from the organic plot. 4.Based on soil respiration activity, none of the organic amendments were able to show a stimulation of soil biological activity in soil from organic or conventional crop rotation plots.