The effect of cover crops on physical, chemical and microbial properties of a sandy loam soil and baby leaf spinach yield

Adam Harber1,2, Gordon Rogers2,1, Daniel K.Y. Tan1

1 Plant Breeding Institute, Sydney Institute of Agriculture, School of Life and Environmental Sciences, Faculty of Science, Biomedical Building C81, The University of Sydney, Sydney, NSW 2006,,

2 Applied Horticultural Research, Biomedical Building C81, The University of Sydney, Sydney, NSW 2006,


Cover or green manure crops have become an important component of sustainable agricultural systems due to their contribution to improving soil condition, fertility and crop growth. This contribution has become vital to intensive vegetable production due to loss of organic matter and soil degradation from erosion. The aim of this experiment was to determine the effect of five short-term winter cover crops on microbial diversity; physical and chemical properties of soil, and on a following baby leaf spinach crop (Spinacia oleracea).  The cover crops used were tillage radish (Raphanus sativa), Caliente mustard 199 (Brassica juncea), oats (Avena sativa), field peas (Pisum sativa) and a mixture of oats and field peas. The cover crops had an effect on soil microbial diversity, chemical and physical properties. All cover crops except mustard significantly increased labile organic carbon (P<0.05); radish significantly decreased penetration resistance (P<0.05) and the mixture increased soil moisture content (P<0.05). Aggregate stability and bulk density were unaffected. The microbial diversity and abundance of the soil changed with cover crops. Cover crops significantly increased the yield of the subsequent baby leaf spinach crop (P<0.05), the highest increase being the radish (3.63 t/ha) and mustard (2.75 t/ha) cover crops. Baby leaf spinach yield was highly correlated with biomass of cover crops (P<0.05), accounting for 85.4% (R2) of variation.  The use of cover crops allows farmers to do more with less inputs, increasing crop productivity across Australia.


The Australian Society of Agronomy is the professional body for agronomists in Australia. It has approximately 500 active members drawn from government, universities, research organisations and the private sector.

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David Marland Photography Southern Farming Systems Agriculture Victoria

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