Studies on the Phosphorus and Potassium Loss on Rubber Plantation Soil
Rubber tracts in China are laid between the north tropics and the south subtropics to enjoy a tropical monsoonal climate,Latosol is the most important soil resources in rubber plantations,most of which are infertile,that lead to slow-growing and low latex yield of rubber tree.It is fearful that,serious soil erosion caused by unreasonable utilization and heavy rainfall make things becoming worse and worse.Phosphorus,nitrogen and potassium losses with runoff are the main contributions to water eutrophication.In order to study how to reduce the nutrients losses and improve the nutrients recoveries,under the condition of natural rainfall,a field experiment treated with different application rates was conducted on rubber plantation by large runoff plots.The results showed that the amounts of P and K losses were affected by rainfall observably,and the K loss mainly occurred during a few times of heavy rain when the rainy season comes before and the first or two heavy rains after fertilization.With the dosage of P and K fertilizer applied increased,the amounts of soluble P and K nutrients showed a positive effect,which was similar to P nutrients combined with runoff sediment,but the K nutrients combined with runoff sediment showed an unconspicuous effect.The soil P and K nutrients mainly migrated with sediment in insoluble forms,proportion for 84.06% and 70.98% separately,while the amounts of soluble nutrients removed with runoff were every little.Besides part lost with surface runoff,the P fertilizer applied to soil could maintain the soil available phosphorus content level at a certain extent,but the K fertilizer mostly lost with rainfall runoff,it showed no significant effect on soil available potassium at this experiment conditions.