The Studies On Recommend Ation Fertilization In Yunnan-guizhou Plateau Pasture

The experiments of fertilization on artificial grassland and nutrient cycling in grazing system were conducted in Langmushan and Beidayrng of Qujing, the crossing site between Yuan-nan and Gui-zhou provinces. The relationship among soil nutrient contents, fertilization rate and herbage production were quantitatively analyzed and the nutrients cycling in grassland animal production systems was dynamically monitored. Based on the findings, the grassland fertilization model and pastoral livestock system nutrient cycling model were forwarded, and the computer recommendation fertilization system was proposed. The main contents of the studies are as follows: The DM yield of herbage was very low when no fertilizer was applied on the grassland. DM yield of white clover at P0(no phosphorus) was only 0.6% of that at P270(270kg phosphorus/bin2), DM yield of perennial ryegrass at P0 was 33% of that at P270 and DM yield of cockfoot grass at P0 was 82% of that at P270. DM yield of white clover highly related to Phosphorus (P) level (r=0.66) and potassium (K) level (r=0.50), but not related to calcium (Ca) level. Soil available P increased with fertilizer application for all treatments The application of calciuin(Ca), magnesiuin(Mg) and P mixtures significantly improved the available P content in soil, and the available P increased with the total P in soil. For non-phosphorus treatment, the available P dropped gradually at the establishment of grassland due to the absorption by the herbage. Soil pH of fertilized plots was increased yearly from 5.36 in 1997 to 5.51 in 2000, which can intensify the solubility of iron (Fe) and aluminum(Al) P and reduce the fixation ability of P by the soil. The available K was raised significantly, especially for ~ up to 30.26mg/i 00g. In view of the relationship function between P and K fertilizers, the Economic and optimum fertilization rate was pure P 95.4kg/bin2, and pure K 13.9kg/bin2 for the mixture grassland of white clover + perennial ryegrass + cockfoot grass, pure P 82.3kg/bin2 and pure K 13.8kg/bin2 for white clover single grassland, pure P 137.7kg/bin2 and pure K 16.4kg/bin2 for perennial ryegrass single grassland at their establishment stage. Sole nitrogen (N) application significantly increased the DM yield of the grassland by 7 1.2% and per kg nitrogen obtained 9.02kg/bin2 of DM increment at the establishment stage of grassland. But this tendency declined year after year. Among the herbage species, ryegrass was effective to N application, the DM increment for per kg N varied from 5.46kg/bin2 in 1998 to 0.36kg/bin2 in 2000. When N, P and K fertilizers were applied on improved artificial grassland at the same time, the interactions between P and K, P and N were significant, and those among N, P and K were not significant in the first year of improvement, the interactions between P and K were significant in the second year of improvement. According to relationship function of fertilizers, the economic application rate of fertilizer was CaMgP 890kg/bin2 and KCL 195kg/bin2 for grasses, and the estimated top DM yield was 13 10kg/bin2 the economic application rate of fertilizer was CaMgP 487kg/bin2 and KCL 82kg/bin2 for legumes and the estimated top DM yield was 2420kg/bin2. According to soil test, nutrient loss from soil in grazing system was visible. The fixation ability of P by the soil was medium to high. absorption of P was 60 percent to 80 per cent. soil available P was 8.01 ppm, phosphorus loss was 14.7k...