頁籤選單縮合
題名 | 嘉義縣土壤與葉片中鉀素及甘藷鉀效之相關研究=Study on Correlations of Soil and Potassium with Response of Sweet Potato to Aded Potash in Chiai District |
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作者姓名(中文) | 何昭仁; 湯兆南; 盛澄淵; 蘇楠榮; | 書刊名 | 中華農學會報 |
卷期 | 62 民57.06 |
頁次 | 頁89-101 |
關鍵詞 | 嘉義縣; 土壤; 葉片; 甘藷; 鉀效; |
語文 | 中文(Chinese) |
英文摘要 | 1. Two trials on the optimum rate of potash and 24 potash observations for sweet potatoes were laid out in Chiayi Prefecture in the autumn crop of 1965, on selected representative calcareous alluvial soils and non-calcareous alluvial soils with textures ranging from fine sandy loam to silty clay loam, for the purpose of studying the quantitative relations between the soil K values and the response of sweet potato to added potash, as affected by types of soil and cultural factors. 2. The correlation beteen the exchangeable K content of soil and the value of available K extrated by Egner's 0.6% Ca-lactate solution at pH 3.6 may be represented by a straight line, being highly significant statistically (Fig. 1, Table 3). 3. The correlations between the response of the root yield to added potash ( in term of the percentage yield value of K0 plots) with the soil exchangeable K determined by neutral N ammonium acetate extraction and with Egner's available K as well as with the percentage saturation of the cation exchange capacity of soil percentage were all found highly significant statistically, when the two distinct groups of soil were combined. But this is not always true when the correlation was calculated separately for the different groups of soil. For both the combination of non-calcareous and calcareous soils and non-calcareous soils alone, the relations between the Egner's available K value and the resposiverness of sweet potato to added potash may be best represented by Mitcherliche-type curves, the correlation coefficients being -0.742 and -0.692, respectively. For calcareous soils, the above mentioned relation may be best represented by a straight line, being also statistically highly significant (r=0.945). (Fig. 2, 3, 4). Since the difference in the trend of stated correlations between the two groups of soil does not not seem to be distinct (Fig. 4) it seems unnecessary to divide soils into different groups for fertilizer recommendation. Since the Egner's available K contents of soils tested were all below 50 ppm K (on air dry basis) except for one, and all soils responded to applied potash, the critical value for soil potassium must be beyond 50 ppm K, provinded 96% of maximum yield is taken as the economic margin. The trend of the curve in Fig. 4 denotes that the critical level of available K is about 60 ppm, when no compost was need. (This value theoretically corresponds to about 125 ppm exchangeable K, when the regression function in Fig. 1 is taken as valid also for the higher range). 4. Although the difference in the trend of correlation stated above was not distinct between the two groups of soil, it seems that the response of sweet potato to added potash tended to be smaller for calcareous soils than for non-calcareous soils, at the same level of available K. 5. Differences in farmer's custom of soil and water managements seem to have been responsible for the deviations from the above mentioned correlations. Poor soil aeration and water drainage may have lowered the absorption rate of native soil potassium. So the percentage yield of K0 tended to deviated downwards from the regression curves, in case of the fields where soil was compact and poorly drained, while in the cases where soil consistense was loose and water supply was suitable, the percentage yield of K0 tended to deviate upwards from the regression curve, showing a lower effect of potash than would be expected from the soil potassium content. This situation is the same with the trials of previous year carried out in Tainan Prefecture. 6. In the two field trials on optimum rate of potash, with a basal addition of 10 tons/ha of compost the optimum rate of potash observed was 160 kg/ha of K2O for the Egner's available K values of 16 and 17 ppm. However, the optimum rate of potash in the absence of compost was between 160-240 kg/ha, based on the evaluation of net profit from addition of different rates of potash, although there was no significant interaction between the effects of potahs and compost. (Fig. 5). The difference in the optimal rate of K2O seems to be around 50 kg/ha for the compost-treated and non-treated cases. 7. The root yields were increased 4-9% by compost, which is highly significant. Higher net profit due to added potash was obtained from the compost-depleted plots than from the compost-applied plots. 8. There was no interference by the difference in the two types of soil with the correlation of yield ratio with leaf potassium. The correlations of root yield with the potassium content of sweet potato leaf, at both 40 and 100 days after planting, may be represented by semilogarithmic curves, being statistically highly significant (r= 0.878 and 0.979). The critical concentration of potassium in sweet potato leaf was found to be about 3.3% (as K) of dry matter between 40 and 100 days after planting, provided 96% of the maximum yield is taken as the economic margin. For a maximum yield, however, the concentration of potassium in sweet potato should be maintained above 3.7%. (Fig.6, 7). 9. Higher leaf Ca and leaf Mg contents were observed at Hsinkang field (calcareous soil) at 100 days after planting as compared with at Tahlin field (non-calcareous soil). For calcareous soil, potash fertilizer seems to depress the absorption of soil calcium and magnesium at the later growth stage, but there was no such remarkable effect for the non-calcareous soil. (Fig. 8, 9). 10. Based on the economic appraisal of potash rates for individual fields, the amounts of K2O for non-calcareous and calcareous alluvial soils are recommended for the autumn crop according to Egner's soil available K values (pH 3.6 calcium lactate extraction) as follows: <20 ppm: 240 kg/ha; 21-30 ppm: 180 kg/ha; 31-40 ppm: 120 kg/ha; 41-60 ppm: 60 kg/ha; >60 ppm: 0-60 kg/ha. For fields receiving 10 tons per ha of compost, the K2O rates may be lowered one grade. |
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