| Based on the research of the long-term fertilization experiment on the dry land of Jiangxi Institute of Red Soil in Jinxian County, Jiangxi Province (1986 ~ 2007), the effects of the long-term fertilization on soil fertility, crop yield and nutrient status have been studied on the condition of red soil. The main results achieved are as following:1. Soil Organic Matter. After continuous fertilization for 22 years, with the treatment of organic fertilizer (NPKM, M), the soil organic matter content showed a remarkable increase than the other treatments, and the combined application of organic manure and nitrogen, phosphorus and potassium fertilizers further enhance the quantity of soil organic matter content. In the past years, more than plenty of chemical fertilizers were employed; especially the unbalanced application of single chemical fertilizer instead of organic manure is not conducive to the accumulation of soil organic matter. However, the combined application of nitrogen, phosphorus and potassium fertilizers with organic fertilizer or the complete application of organic fertilizer has significant impact on increasing soil organic matter content, which is far better than single application of fertilizer. After long-term fertilization, the variation trends of both soil total nitrogen and organic matter are basically consistent. While if chemical fertilizers were used without any supplement of organic fertilizers, by and by the soil organic matter content will gradually decline, even affecting the growth of crops.2. Soil Nitrogen. Continuous non-use of nitrogenous fertilizers for 22 years will lead to the decline in soil total nitrogen; the application of all treatments of nitrogen fertilizer can maintain soil nitrogen to some extent, and the application of organic manure or the combined application of chemical fertilizers with organic manure has the most obvious effects on improving soil total nitrogen content. As to Ck, as year goes by, soil total nitrogen content has displayed a continuous drop. After 22 years'located fertilization, the Soil Alkali-hydrolyzable Nitrogen content with nitrogen fertilizer has a very significant increase, and along with the enhancing dosage of other nutrients, the positive effect of increasing nitrogen content becomes more pronounced. Nevertheless, referring to the P and CK treatment without nitrogen fertilizer, the Soil Alkali-hydrolyzable Nitrogen content is lower yet obvious.3. Soil Phosphorus. The experiment results showed that, with the application of organic manure treatment (NPKM, M), the soil total phosphorus content achieves a very significant increase respectively, particularly for the NPKM treatment. But for the non-P treatment, the soil total P has decreased; when a certain amount of phosphorus is employed in crops planting, the soil total phosphorus mostly presents augmenting. For the mixed-use of fertilizer and organic manure, soil total phosphorus raised markedly. Application of organic manure can evidently increase soil total P content, whose effect is better than chemical P fertilizer. In addition, more obvious increases take place concerning soil available phosphorus. Without P treatment, the soil available phosphorus has decreased or unchanged; but with P treatment, the soil available phosphorus has shown a marked increase and organic fertilizers can obviously boost soil available phosphorus and total phosphorus content.4. Soil Potassium. Continuous fertilization for 22 years would result in the gradual decreasing of soil total potassium content directly connected with the various fertilizations, which leads to a lack of potassium in red dry land. The soil available K includes the majority of exchangeable K and soil solution K. Non-use of potassium fertilizers will give rise to a great reduction in soil available K. Therefore, the application of organic manure or chemical potassium fertilizer is an effective measure to maintain and improve soil available potassium, and the effect of potassium fertilizer is superior to organic fertilizer.5. Soil pH. The soil through the treatment of organic fertilizer (M, NPKM) has higher pH than the rest of soil through the treatment of chemical fertilizer, the contrast of which displays a very significant level that enhance the buffering capacity and pH of soil. But, the single or partial application of Nitrogen fertilizer (N, NK) will lead to the lowering of soil pH among all treatments, and also proves to be conspicuous in the experiment. In particular, long-term single application of nitrogen fertilizer will reduce soil pH and bring about soil acidification. Thus, the results show that the partial use of nitrogenous fertilizers can accelerate soil acidification and reduce the pH value: in the condition of low-nitrogen fertilizer, the level of acidification is lower, and the soil pH is higher; but with the increase in nitrogen application rate, the degree of acidification is greatly increased, and the pH follows declining.6. Soil bulk density and porosity. After 22 years'fertilization, different fertilizer treatments of the soil would not contribute to significant difference in soil bulk density and with CK also no significant differences. Neither would soil porosity and with CK no significant differences.7. Corn production. After 22 years'fertilization, it demonstrated a declining trend of yield, while a significant yield increase attributes to combined application of organic and inorganic production of corn. Among several treatments, the highest grain yield belongs to NPKM through statistical analysis and comparison with other processing, which reaches to a significant level; the following is 2NPK and then M treatment, respectively, compared with other treatments are up to the very significant level. After 22 years'fertilization, the majority of biological production is rising; the remaining treatments mostly lead to a certain production level with fluctuations. 22 years'production test results showed that all fertilizer treatments lead to a better yield than non-fertilizer production. In the respective of synthesis, 2NPK and NPKM crown themselves among these treatments in terms of highest production. 8. Corn nutrients. Compared continuous fertilization of 22 years with 1 year's fertilization of grain crops, the former one suffers decreasing of nitrogen, phosphorus and potassium nutrient content. And a conspicuous difference emerges between the single application of fertilizer and mix-fertilization; Contents of nitrogen and potassium are higher in the section of straw, most of them went through decrease of the phosphorus content. After 22 years continuous fertilization, NPKM and 2NPK treatments lead to higher total nitrogen than other treatments. The content of phosphorus in different treatments do not vary sharply compared with CK. Balanced fertilization can give rise to lower total potassium content. After 22 years continuous fertilization, it is demonstrated a higher nitrogen content in the straw and reached a significant level. While CK is not the same came when employing different treatment. Straws with different treatments displays far slime difference in the potassium content, N, NP with non-K treatment displays lowest level and reach a significant level; treatments of M, NK, NPK show higher content than CK and reached a significant level.In conclusion, synthesizing all variations of soil fertility, crop yield and nutrient, regarding to the present manuring system, organic and inorganic fertilizer (NPKM) is believed to be the best solution, along with focus on the balanced application of nitrogen, phosphorus and potassium fertilizers. In the meantime, on the basis of the existing volume of potassium fertilizer, the usage of the chemical potassium fertilizer or organic fertilizer should be appropriately increased.
|
PDF Full Text Request