Effects of restorative agroecosystemson soil characteristics and plant productionon a degraded soil in the GeorgiaPiedmont, USA

This work presents the results of a three-year field study of agroecosystems designed to restore soil organic matter (SOM) todegraded soils of the Georgia Piedmont. The systems combine a suite of management practices previously demonstrated toincrease SOM when studied individually, and examine the effects of these techniques when used in combination in acropping systems context on soil characteristics, crop production and weed biomass. The systems’ components includeorganic management, alley cropping with perennial legumes, conservation tillage, use of winter cover crops, straw mulchand two compost application rates. Vegetable crops grown were a rotation of okra, hot pepper and a corn and winter squashintercrop. The systems were not able to maintain soil C or N without the addition of compost. Systems incorporating alleycropping, organic management, conservation tillage and compost maintained soil C, and increased in soil C when mulchwas not applied. In organic, conservation tillage without alley cropping, soil C did not change significantly, even withannual 44.8Mgha- 1 of compost additions. Patterns for soil N followed those of soil C. The study demonstrated that alleycropping can maintain and sequester soil C and N beyond organic conservation tillage alone, and more than conventionallytilled, chemically fertilized treatments. Crop yields did not vary by treatment due to high variation within treatments. Wintercover crop residue provided an effective weed barrier for 4 to 6 weeks in the spring, but additional hand weeding wasrequired throughout the summer. The results of this systems-level study demonstrated interactions between managementpractices when used in combination that would not have been observed when studied individually. It also demonstrates thatagroforestry techniques, conservation tillage and compost applications can increase soil C in degraded, clayey soils whilethey are in cultivation