中部粘板岩冲積土若干土系之特性與水稻生育、收量之關係

Abstract

就本省中部粘板岩沖積土，於民國62年選8個地點，民國63年34個地點之水田，在標準施肥管理下比較水稻生育、收量之差異及有關土壤特性，結果如下： 1. 土壤調查所分排水良～尚良（田中、平和各系）、不完全（二水、二林、鹿港各系）與不良（秀水、社頭各系）各級別土系之田問滲透率（第一、二期作各於插秧後40及30天左右測定），平均各為0.80、0.35及0.06cm/day；差異顯著，顯示土壤調查以剖面形態之觀察區分排水性之良否頗能反映田問的實際排水情形；惟同屬排水不完全之各土系田間滲透率，則尚依質地剖面之粗細而有差異，如管嶼厝系＞二水（二林）系＞鹿港系是。 2. 稻谷收量亦依排水良～尚良＞不完全＞不良之次序而差異，但以第二期作較為顯著；其各級別土系之平均收量各為5.51、5.02及4.53ton/ha，差異均達顯著標準。同屬排水不完全之各土系平均收量亦以滲透率較高之管嶼厝系為高，慘透率較低之鹿港系為低。 3. 就34個地點之水稻生育、收量與12種土壤特性，求各種單相關及複相關，亦顯示第二期作水稻之牛育、收量與田問慘透率之關係最為密切。 收量低落地點之水稻，營養上除鉀素含量稍低外，並無任何其他要素之顯著不正常情形。表面排水或輪作等均對水稻少育有顯著的正效果，可見就中部粘板岩沖積土上述土系的範圍而言，排水性可認為係影響水田生產力之主要因素。 4. 一般言之，排水性較差的土系，表土中均有較高之pH值、CEC、有機質及碳酸鈣含量，蓋其地勢較低使然。又老沖積土與新沖積土比較（如二林系與二水系），亦有較高之有機物及CEC，蓋其風化時問較長之故。惟此程度之肥力差異或為排水性所限，或為集約之施肥管理所彌補，對於現實水田收量均非重要因素。 A total of eight and thirty four localities respectively, in 1973 and 1974 were set up on some wide-spread soil series of slate alluvial origin in central Taiwan with different drainage conditions, ages of deposition, and ranging from moderately coarse to fine in texture profiles, The growth and yield of the rice plants in these localities were compared under the standardized cultural practice and with ample application of N P K fertilizers, and the soil characteristics associated with yield difference were studied. 1. The mean natural permeabilities measured before the practice of field drying of the soil series of different drainage classes as classified by soil survey, i. e., well to moderately well, imperfect and poor were 0.80, 0.35 and 0.06 cm/day, respectively showing significant differences among each other. Thus the drainage classes determined by the morphological characteristics of profiles quite reflect their respective drainage status. However considerable variations of permeability were also observed among the soil series of same drainage class hut with different texture profiles, e. g., the coarse textured Kuanhsutseu series has a significantly higher permeability compared with the fine textured Lukang series although both of them belong to the imperfect class. 2. The grain yields also differ among the soil series of different drainage classes according to the following order, i. e., well to moderately well>imperfect>poor, particularly in the second crop and the means were 5. 51, 5.00 and 4.53 ton/ha, respectively. Considerable differences in yield, however, were also observed among the soil series of the imperfect class but with different texture profiles, e. g., the yield of Kuanhsutseu series was significantly higher than that of Lukang series which was in accordance with the greater permeability of the former compared with that of the latter. 3. The studies of simple as well as multiple regressions between yields and various soil characteristics also revealed significant positive correlation between permeability and rice yield in the second crop. There were no particular disorder of any nutrient elements observed in the low yielding rice plant except that potassium content was sometimes lower slightly. Significant improvement in rice growth was observed by the practice of surface drainage or rotation in such cases. Thus the drainage status of soil can be considered most important governing rice yield in this area as far as the scope of soils studied. 4. In general, the soils with poor drainage have higher values of pH, CEC and contents of organic matter and CaCO3 which might be due to the physiographies of the localities. Moreover, the older alluvial soils also have higher organic matter content and CEC than the rescent alluvials soil (e. g., Erhlin series compared with Erhshui series) due to the time of weathering longer. 1-lowever rice yields were not affected by these extents of fertility difference due to the difference easily covered by the intensive fertilization practice prevailed or by the drainage factor dominating.