长期定位施肥对土壤磷、钾素动态变化的影响

Effects of long-term fertilization on dynamics of phosphorus and potassium in soil

23年定位施肥试验的结果表明,不施肥和单施氮肥的土壤,其有效磷质量分数迅速下降,前3年比播前降低约50%,自第7年开始比播前降低2/3左右,降至4～5 mg/g之后处于稳定状态。土壤全磷质量分数始终保持在0.40～0.50 g/kg的水平,有机磷略有增加。施有机肥以及有机肥与氮肥配施的土壤,其有效磷和有机磷质量分数增加显著。单施氮肥的土壤,其速效钾、缓效钾质量分数均降低,全钾质量分数变化不明显。在每年每公顷单施含钾150.0 kg、300.0 kg的有机肥或与138 kg、276 kg氮素配施的土壤中,以单施含钾300.0 kg的有机肥的土壤的钾素盈余量最多,并随配施氮量的增加而盈余量减少。试验23年后的土壤,其钾素盈余量与土壤速效钾、缓效钾质量分数均有极显著的相关性,而与全钾质量分数的相关性不大。

A fertilizer experiment was conducted at a fined location for 23 years. The results showed that the content of soil active phosphorus was decreased more rapidly in the treatment of applying no fertilizer than that of applying nitrogen fertilizer only. The content of soil active phosphorous was decreased by 50% in the first three years and about two-thirds from the seven year on wards, compared with that in the previous year. Finally, it was stabilized after being decreased to 4～5 mg/g. The total phosphorous was maintained 0.40～0.50 g/kg from the beginning to the end, and the content of soil organic phosphorous increased slightly. In the treatments of applying manure and manure mixed with nitrogen fertilizer, the increase in soil active phosphorus and organic phosphorous was very notable. The content of active phosphorous in the treatments of applying manure (lower and higher) and mixed with nitrogen fertilizer (lower and higher) were increased by 107.09 mg/g, 104.01 mg/g, 76.50 mg/g, 162.54 mg/g, 152.40 mg/g, and 155.01 mg/g respectively, organic phosphorous were increased by 93.06 mg/g, 96.40 mg/g, 80.13 mg/g, 100.93 mg/g, 126.16 mg/g, and 122.29 mg/g from 1980 to 2001. As for the treatment of applying nitrogen fertilizer only, the available potassium and slow-release potassium in soil were decreased, the dynamics of total potassium was not notable. The surplus of potassium in the treatment of applying manure (300 kg/hm2 of potassium ) was most in treatments of applying lower manure (150 kg/hm2 of potassium), higher manure (300 kg/hm2 of potassium) and mixed with lower nitrogen fertilizer (138 kg/hm2 of nitrogen), higher nitrogen fertilizer (276 kg/hm2 of nitrogen), and the surplus of potassium decreased as application of nitrogen fertilizer increased. After the experiment was done for 23 years, the surplus of potassium was significantly related to the soil available potassium and slow-release potassium, on the other hand, there was not a notable relation between the surplus and soil total potassium.