Litter decomposition in fertilizer treatments of vegetable crops under irrigated subtropical conditions
ROTTMANN, N., SIEGFRIED, K., BUERKERT, A., JOERGENSEN, R.G. (2010)
Biology and Fertility of Soils 47, 71-80
Abstract In the coastal Batinah plain of Oman, a litterbag experiment was carried out in an irrigated field, investigating the effects of organic fertilization and mineral fertilization on the cultivation of carrots and cauliflower. Two straw varieties and two green-harvested crops were used, simulating the properties of green manures. The loss of C in the litterbags declined in the order maize (−94%) > alfalfa (−89%) > wheat (−80%) > canola (−69%). For all these materials, the concentration of muramic acid, as an indicator of bacterial C, as well as galactosamine was generally increased in comparison with the initial values. In contrast, fungal glucosamine and consequently also the ratio of fungal C/bacterial C declined for canola and wheat straw. The loss of N, P, and S was generally smaller than that of C and showed strong substrate-specific patterns. Fertilization and crop cultivation had no effect on C losses. Organic fertilization resulted in significant increases in S, Mg, and Al in the litterbags in comparison with mineral fertilization. Cultivation of carrots led to significantly lower ash, N, P, Ca, K, Na, and Al concentrations than cultivation of cauliflower. Organic fertilization and carrot cultivation both led to stronger fungal colonization of the litter retained in the litterbags in comparison with mineral fertilization and cauliflower cultivation, respectively. More information is required on the interactions between initial plant surface colonizing microorganisms and soil-derived colonizers.