轉作田玉米肥料需要量與土壤肥力之關係

Fertilizer Requirements of Corn in the Drained Paddies Related to Soil Fertility

連深(S. Lian)

《中華農業研究》 35卷3期 (1986/09) Pp. 318-334

https://doi.org/10.29951/JARC.198609.0008

摘要

本試驗於兩年期間舉辦秋作試驗16處和春作試驗13處，探討臺農351號玉米在轉作田之肥料需要量與土壤肥力之關係，並概定各種要素之需肥診斷基準如下：
(1)各地之玉米施肥效應以氮和磷較高，鉀較低。秋作之氮素需要量平均爲180公斤／公頃左右，其經濟用量平均則約爲165公斤／公頃。氮肥效應之土壤間差異很大，但與有機質含量亦有粗略之負相關；故個別地黯之氮需要量可由土壤有機質含量和該地之收量潛力決定。
(2)秋作磷醉的經濟用量平均在100公斤／公頃左右。各地磷肥效應與土壤有效磷測定值有密切關連，其中與Olsen氏法之測定值關係較佳。土壤磷之診斷基準與磷肥之推薦量暫定如文中表4。
(3)秋作鉀(K2O)之經濟用量平均約爲75公斤／公頃。各地之鉀肥效應亦與土壤之置換陸鉀或孟立克氏鉀含量有粗略相關。土壤鉀測定值之診斷基準與鉀肥之推薦量暫定如文中表5。
(4)收量6.5噸／公頃之玉米植株三要素吸收量爲N、P2O5、K2O各120、45、100~120公斤／公頃；其中子實之三要素奪取量各爲85、35、24公斤／公頃。故N、P2O5之推薦量各165和100公斤／公頃實際上均已超過此等要素之植株全吸收量或子實之奪取量；吸收剩餘之磷肥固可蓄積於土壤中而提高其磷肥力，但剩餘之氮素在土壤中之動向却值得注意。
(5)以上三要素推薦量係以中南部秋作爲主所定。由於北部及東部爲主之春作收量水準顯著低於秋作，其三要素需要量亦較然作爲低；氮、磷醉、氧化鉀平均需要量各在100~150、50~100、50公斤／公頃左右；上述各表中之不同土壤肥力級別磷、鉀推薦量於春作時亦應酌量減少。
又以上各種施肥推薦量係以整地栽培爲主之情形下所定；在不整地清形下因氮肥的揮失、固定等較多而土壤氮的礦化供應卻減，其氮推薦量一般應較整地者酌予增高。
(6)玉米葉鎂濃度與土壤中之置換性鎂含量關係不大，卻與其置換性鎂／鉀比及葉鉀濃度關係密切，各呈顯著的正、負相關。故土壤中之置換性鎂含量很低固可導致玉米缺鎂，鉀肥施量過多亦會導致缺鎂現象。
在本試驗中雖有少數地點之玉米呈缺鎂徵狀，但施鎂之效果却甚有限，詳細情形尚待進一步試驗。

並列摘要

To meet the current situation of large extension of corn in the drained paddies under the Rice Crop Substitution Program, a trial on the fertilizer requirements of the crop in the drained paddies was conducted on 16 and 13 locations, respectively in the fall and spring crop seasons during 1983-1985.
The cultivar tested was Tainung No. 351 which is a mid-maturing variety with growth duration of 120-130 days bred for the Program. The locations of the fall crop experiment were mainly distributed in the central and southern parts of the island, while those of the spring crop experiment were distributed in the eastern, northern and central parts of the island; among the locations, two in the central part of the island were conducted with both crops of the experiment. The results are as follows.
1. In the fall crop, the corn responds to N and P in most of the locations, whereas the response to K is smaller in most of the locations. The mean economic rates for N, P205 and K20 are 165, 100 and 75 kg/ha, respectively. As the responses to P and K fertilizations are correlated to Olsen P and Mehlich K(or exchangeable K) respectively, the optimum rates for individual soil are recommended according to a soil testing criteria obtained from this study.
2. The yields of the fall crop on these locations ranged 5.0-8.4 t/ha, showing a large variation among the soils. The phosphate fertility as well as physical properties such as compactness of soils are considered as important fertility factors to be studied further.
3. The responses of corn to N P K as well as the yields are significantly lower in the spring than in the fall crop. The mean optimum rates for N, P205 and K20 in the spring crop are 100-150, 50-100 and 50 kg/ha, respectively.
4. The Mg concentration in leaves does not correlate with the content of exchangeable Mg in soils, however, it correlates positively with the ratio of exchangeable Mg/K in soils or negatively with the K concentration in leaves.
There were some locations with low ratio of exchangeable Mg/K in soil showing Mg deficiency symptoms in the plant, however, the response to the application of magnesium sulfate was rather limited.