Cover crop performance in an apple orchard and its effect on the macro-elements and carbon levels in a loamy sand

Abstract

Five treatments were applied in a newly established orchard on a loamy sand near Vyeboom, South Africa. Treatment 1 (T1): chemical control in the tree row from bud break to harvest, with dwarf fescue (Festuca arundinaceae Schreb.) slashed regularly in the work row. Treatment 2 (T2): ‘Saia’ oats (Avena strigosa Schreb. ‘Saia’) in the work row, with full surface chemical control (CC) applied early October and the beginning of December. Treatment 3 (T3): pink serradella (Ornithopus sativus Brot. ‘Emena’) in the work row and a subterranean clover (Trifolium subterraneum L. ‘Campeda’) in the tree row and CC. Treatment 4 (T4): a mixture of ‘Saia’ oats and pink serradella in the work row and CC. Treatment 5 (T5): a mixture of canola (Brassica napus L. ‘AVGarnet’) and ‘Caliente 199’ brown-mustard (Brassica juncea (L.) Czern. ‘Caliente 199’) in the work row and CC. T2 was the best performing treatment for the control of the winter and early summer growing weeds, while T1 controlled the late summer growing weeds the most effectively. T4 caused the highest increase in soil organic carbon, while T3 achieved the highest release of total inorganic N during the growing season (November to January).