Effects of restorative agroecosystems on soil characteristics and plant production on a degraded soil in the Georgia Piedmont, USA

Published source details Jacobsen K.L. & Jordan C.F. (2009) Effects of restorative agroecosystems on soil characteristics and plant production on a degraded soil in the Georgia Piedmont, USA. Renewable Agriculture and Food Systems, 24, 186-196.
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This study is summarised as evidence for the following.

	Action	Category
	Convert to organic farming Action Link
	Change tillage practices Action Link

Convert to organic farming

A randomized, replicated experiment in 2004-2007 on sandy-clay loam in Georgia, USA (Jacobsen & Jordan 2009) found soil carbon was lower under organic management with strip tillage (8.0 MgC/ha) than under alley crop management (13.4 MgC/ha). Soil nitrogen followed a similar pattern. Alley cropping stored more soil carbon than conventional tillage (10.7 MgC/ha). Soil microbial biomass was not affected. Crop yields were highest under alley cropping (3932 and 5060 kg/ha okra Abelmoschus esculentus and hot pepper Capsicum annum respectively) except the corn Zea mays/squash Curcurbita moschata intercrop, which was highest under organic management with strip tillage (4087 kg/ha). Four treatments included: alley cropping with strip tillage, organic management with conservation tillage, conventional tillage and fertilizer, and mowed fallow (4, 4, 8 and 6 replicates respectively). Mimosa Albizia julibrissin hedges were 5 m apart with crops grown in between in 15 cm wide by 15 cm deep furrows. Compost and straw mulch were added to each treatment. Vegetable crops were grown in rotation with winter cover crops: okra, hot pepper, corn, squash, crimson clover Trifolium incarnatum, pea Pisum sativum and rye Secale cereale. Soils were sampled each year to 15 cm depth, and measured soil carbon, nitrogen and microbial biomass.
Change tillage practices

A randomized, replicated experiment in 2004-2007 on sandy-clay loam in Georgia, USA (Jacobsen & Jordan 2009) found higher soil carbon under strip tillage with alley cropping (13.4 Mg C/ha) compared to strip tillage with organic management (7.7 Mg C/ha) and conventional tillage (10.7 Mg C/ha). Soil microbial biomass was not affected. Crop yields were highest under strip tillage with alley cropping except the corn Zea mays/squash Curcurbita moschata intercrop, which was highest under strip tillage with organic management. It was not clear whether these effects were due to tillage or other management practices. Four treatments included: alley cropping with strip tillage, organic management with strip tillage, conventional tillage and fertilizer, mowed fallow (four, four, eight and six replicates respectively). Vegetable crops (okra Abelmoschus esculentus, hot pepper Capsicum annum, corn, squash) were grown in rotation with winter cover crops: crimson clover Trifolium incarnatum, pea Pisum sativum and rye Secale cereale. Soils were sampled each year to 15 cm depth, and measured soil carbon, nitrogen and microbial biomass.