| By pot experiment and laboratory analysis, the article focuses on the introduction of fertilizer deep placement precision positioning concepts and new technologies such as environmental protection and efficient slow-release fertilizer and studies the available soil nutrients of rice cropping systems, dynamic changes of field leakage water and rice NPK, rice growth and yield status, NPK fertilizer utilization under the condition of precision positioning in deep fertilizing, so as to ascertain the dynamic changes of NPK in rice cultivation system "soil-water-rice" and the influence of fertilization depth on biological effects of rice, to reveal the relationship of deep application of fertilizer and use efficiency, and to provide technical support for the mechanized application of precision fertilizer technology. The main findings are as follows:(1) At different growth stages of rice, available nitrogen and available potassium levels become raised firstly and then decreased, available phosphorus levels firstly decrease dramatically and then increase slightly. Nitrogen, potassium and phosphate levels of fertilization treatments on soil of 9cm are increased 3～20mg/kg,2～10mg /kg,0.5～0.9mg/kg than levels under no fertilizer and other fertilizer treatments. The variation trends of TN and TK in water leakage are similar. The levels of TN and TK decline with the increasing of fertilization depth. TN in percolating water is mainly NH4-N, accounting for 80% to 90%. TP trend is not obvious. Rice NPK content in different parts has relatively large difference, which is shown as leaf> spike> roots. Rice NPK levels of different growth stages under deep fertilization are higher than those without fertilization, and rice NPK under fertilizer treatments on soil of 9cm is always at the highest level.(2) Deep application of fertilizer can promote rice tillering, increase plant height and the length of roots. Fertilization depth has shown positive correlation between longitudinal length of roots and plant height. S9 treatment has maintained a high tiller, its effective tillering rate is 4.55% higher than that of S0,0.65%-2.22% higher than the other fertilizer treatments; the ratio of plant height is 12.38% higher than that of SO treatment, an increase of 3.51%～10.45% compared with fertilization treatment; root longitudinal length increases 29.7% to 44.9% over the SO treatment, and is 6.47%-21.37% higher than fertilization treatment. With the increasing depth of fertilizer and plant dry matter accumulation, the trend is shown as S9> S6> S3> SX> SO treatment. Deep application of fertilizer is good for the high production of rice yield factor. Total grain number per spike and seed-setting rate increase parallelly with fertilize depth; biological yield and harvest index fertilization treatments are significantly higher than those without fertilization. Under certain circumstances of fertilizer,9cm fertilization rice growth and yield are better than other treatments.(3) Deep application of fertilizer can increase the uptake of NPK by rice straw, rice and root. With the increase of fertilizer depth, N, P, K fertilizers use efficiency and agronomic efficiency are significantly increased. The absorption of N by Rice straw and rice are shown as S9> S6> SX> S3> S0, NPK absorption for roots is shown as S9> S6> S3> SX> SO treatment. Compared with the SX treatment, the use efficiency under S6, S9 fertilizer treatment has increased N 28.26%,74.14%, P 39.98%,66.42%, K 3.53%～31.95%; agronomic efficiency has increased N 27.65%,47.98%, P 27.56%,47.98%, K 27.55%,47.93%. Considering the supply capacity of soil NPK fertilizer nutrient leakage and fertilizer utilization,9cm is the best place for deep fertilization. |
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