EFFECTS OF CRUSHED MAIZE STRAW RESIDUES ON SOIL BIOLOGICAL PROPERTIES AND SOIL RESTORATION

Agriculture soils in the Mediterranean need restoration and rehabilitation after 10 millenia of use and abuse. Maize straw residues crushed at three sizes [<1 (C1), 1-10 (C2) and >10cm (C3)] at 5Mgha(-1)y(-1) and with and without urea (150kgNha(-1)) were applied during a period of 3years for the purpose of restoration of a Typic Xerofluvent located near Cordoba (Spain). The effect on the vegetal cover and biological properties (microbial biomass, soil respiration and enzymatic activities) were determined. The size of the crushed maize residues (particle size <1cm) and N supply influenced in the evolution of soil biological properties and vegetal cover. The stimulation of microbial biomass, soil respiration, dehydrogenase, urease, -glucosidase, phosphatase and arylsulphatase activities was higher in C1+N-amended soils for 149%, 163%, 88%, 243%, 135%, 71% and 103%, respectively, compared with C2+N and for 258%, 269%, 183%, 385%, 282%, 191% and 183%, respectively, compared with C3+N. Vegetal cover from the C1+N treatment was 114%, 178%, 294%, 376%, 449% and 751% greater than that in C2+N, C3+N, C1, C2, C3 and control soil. These results suggested that under dry climatic conditions, the application of crushed maize straw finely crushed+N fertilizers improved the soil biological properties and also favour the appearance of spontaneous vegetation, which will protect the soil and will contribute to its restoration. Consequently, the addition of the crushed maize straw finely crushed+N fertilizers may be considered a good environmental strategy for recovery of degraded soils. Copyright (c) 2014 John Wiley & Sons, Ltd.