Influence of Pinus radiata stocking density on the organic matter pools and mineralizable nitrogen in an agroforestry system.
1989
Sparling G.P. | Hart P.B.S. | Hawke M.F.
The influence of increased stocking densities of Pinus radiata on the amounts and distribution of organic matter and mineralizable nitrogen (N) in the surface horizons of soil was examined in an agroforestry plantation. Increased stocking density of P. radiata caused little change in soil pH, slightly decreased the organic C content of the mineral soil, but caused a marked drop (43% relative to pasture) in mineralizable-N, as assessed by an anaerobic incubation method. There was a strong correlation between the amount of mineralizable-N and the microbial biomass C. The reduction in mineralizable-N under high densities of P. radiata is probably a consequence of the decline in clover component of the pasture because of competition for light and nutrients. The lower densities of pine or the twin-row planting pattern where substantial pasture production was still possible, had comparatively little impact on mineralizable-N and organic matter content.
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