施肥對不同生長期玉米生長與植物體中氮組成之影響

Abstract

This experiment was to study the effects of different kinds of fertilizers on the growth, nitrogen uptake. nitrogen composition in various organs of corn plant during growth. The application rates of fertilizers were 140- 80-80 (N-P：0s-K20) kg ha'1. There were seven treatments: 1. chock (CK); 2. chemical nitrogen fertilizer plot (Chem-N); 3. compost plot (Comp)； 4. compost accompanied with one- third of nitrogen as chemical fertilizer plot (Comp + ]/3 N); 5. compost accompanied with two-thirds c)t nitrogen as chemical fertilizer plot (Comp + 2/3 N); 6. green manure accompanied with one-third of nitrogen as chemical fertilizer plot (GM + 1/3 N); 7. peat accompanied with one-third of nitrogen as chemical fertilizer plot (Peat + 1/3 N). Corn was sampled at different growth stage. The concentrations of the nitrate nitrogen, insoluble nitrogen, and total nitrogen were analyzed. The results indicate that application of readily available nitrogen increased corn growth, nitrogen absorption, and the concentrations of different forms of nitrogen in the plant as compared with check plot. The growth and nitrogen absorption of corn plants of the Chem-N treatment were higher than those of the other treatments. The growth and nitrogen absorption of Comp. Comp + 1/3 N, and Comp + 2/3 N treatments increased with the increase of application rate of chemical nitrogen fertilizer. When nitrogen was supplied by organic manure without chemical nitrogen fertilizer, the growth of corn plant was significantly lower than that of the Chem-N treatment. Application of organic manure accompanied with chemical nitrogen fertilizer significantly increased the growth and nitrogen absorption of the corn plants. The growth of corn plants of Peat + 1/3 N treatment was smaller than that of Chem-N treatment. The growth of corn plant of GM + 1/3 N treatment was the same as that of Comp + 2/3 N treated- plot，whose chemical nitrogen application rate was twice that of the former. The nitrate and insoluble nitrogen concentrations of the CK and Comp treatments were the lowest of all treatments, probably due to the lower concentration of readily available nitrogen in soil. The low nitrate nitrogen concentrations of com plants at maturity stage were probably due to the high reduction and the low absorption rates of nitrate in the plants. The concentrations of nitrate nitrogen and reduced soluble nitrogen in leaf blade were lower than that of stalk and sheath. However, the concentrations of insoluble nitrogen and total nitrogen of the former were higher than those of the latter. There was no significant difference in the concentration of total reduced soluble nitrogen among various treatments. 本研究以不同的有機肥料配合化學氮肥之施用，探討其對不同生育期之秋作玉米之生長、氮吸收與氮組成的影響，以做爲肥料施用之參考。施肥量爲140-80-80 (N- P2O5-K2O) kg ha-1，所設定的處理爲1.對照區(CK)；2.化學肥料區(Chem-N)；3.堆肥區(Comp)；4.堆肥與1/3化學氮肥區(Comp + 1/3 N)；5.堆肥與2/3化學氮肥區(Comp + 2/3 N)；6.綠肥與1/3化學氮肥區(GM + 1/3 N)；7.泥炭與1/3化學氮肥區(Peat + 1/3 N)。玉米於不同生育期採樣，經洗淨、分開不同的器官、烘乾、稱重、磨碎及化學分析。結果顯示有效性氮的供應量顯著影響玉米的生長、氮的吸收及植物體中各種不同型態氮的濃度。提供有效性氮最多的Chem-N處理之玉米的生長與氮的 吸收量有較多的趨勢，施加堆肥之Comp、Comp + 1/3 N及Comp + 2/3 N三處理則隨 添加之化學氮肥量增加而增加其生長與氮 的吸收。Chem-N處理之玉米的生長與氮的吸收顯著高於Comp處理者。有機資材配合化學氮肥的施用可顯箸影響玉米的生長與氮的吸收，豬糞堆肥在生長初期所能提供之有效性氮少，且於施入土壤後可能發生氮的生物固定化作用，使可以爲玉米吸收的有效氮因而減少。泥炭較不易分解，故 Peat + 1/3 N處理所施用之化學肥料肥效較高。田菁綠肥在土壤中分解甚快，施於土壤中可以很快提供氮素，故其肥效與化學氮肥甚爲接近。植物體中硝酸態氮與不溶性氮濃度的高低隨箸土壤中有效性氮的多寡而變化。CK與Comp兩處理的硝酸態氮及不溶性氮濃度顯箸較低。於雄穗抽出期以後所有處理之硝酸態鉍濃度均極低，甚至無法檢出。不同生育期時在葉片中的硝酸態氮及溶性還原態氮濃度均比莖稈低，但其總氮與不溶性氮濃度會高於莖稈中者。各種處理對植物體中不同部位的可溶性還原態氮的濃度並無顯笤差異的影。