長期連用矽酸爐渣對水稻收量和土壤化學性質之影響

Effects of Long Term Application of Siliceous Slag on Paddy Yield and Chemical Properties of Soil

連深(S. Lian) ； 王鐘和(C. H. Wang)

《中華農業研究》 32卷2期 (1983/06) Pp. 185-199

https://doi.org/10.29951/JARC.198306.0010

摘要

本研究綜合檢討9處矽酸爐渣連用試驗經歷5年（10作）及1處矽酸爐渣、稻藁連用試驗歷經6 1/2年（13作水稻）之收量結果，並分析矽酸爐渣之連用對土壤化學性質之影響。
試驗地點分佈西部各縣、土壤均屬酸性，9處矽酸爐渣連用試驗之處理爲(1)對照區；不施矽酸爐渣，(2)矽酸爐渣每期作每公頃1.5公噸，(3)矽酸爐渣每期作每公頃3公噸，但自第7作（69年第二期作）起將(2)及(3)處理各分爲二半，一半繼續施用矽酸爐渣（照原量），另一半則停施以觀矽酸爐渣之殘效及續施效果。另一處矽酸爐渣，稻藁連用試驗則以稻藁之掩埋與否（即稻藁每期作每公頃0及5公噸）爲主處理，矽酸爐渣之施用與否（即爐渣每期作每公頃0及2公噸）爲副處理，亦自第7作起以試驗田之一半停施矽酸爐渣以觀殘效。以上試驗各處理區，均依標準施肥法施用足量之三要素肥料。結果如下：
1．矽酸爐渣之肥效除了其施用初期略低外，其餘歷作平均增收率爐直1.5及3噸區各爲5~15及8~20%，此種矽酸爐渣肥效之不同年度變異主要係與對照區之收量有關（成負相關），而與爐渣連用年數之累加無關。即爐渣之連用雖達9~12作，尚看不出爐渣之肥效有任何隨著連用年數之增加而增加或降低之顯著趨勢。
2．連用矽酸爐渣之稻田對其次作水稻常有顯著的殘效，但隨著停施時間之經過殘效却有顯著降低趨勢；爐渣連6作用後其在土壤中之累積用量已甚可觀，但在第7作其停施之效果即甚顯然，亦即在第7作所表現之殘效已顯著低於續施之效果。矽酸爐渣連用10作期間，其1.5公噸區和3公噸區之增產效果亦始終維持一定差距，即無論連用年數之增加始終以3公噸區之效果較大。
3．矽酸爐渣每公頃每作連用1.5及3公噸，於第7作後表土pH值平均各約提高0.4及0.8單位，有效矽含量平均各約提高130及300ppm。繼續施用爐渣並無繼續顯著提高土壤pH值及有效矽含量趨勢，惟其停施後之降低却甚明顯；矽酸爐渣連用6作後其土壤中之矽酸累積用量已甚可觀，但爐渣在第7作時停施却使土壤中之有效矽酸含量顯著降低，土壤中之可還元性錳含量亦有同樣跡象。以上結果在稻體中亦有同樣反映。
由土壤中有效矽之投入量，水稻之吸收量及土壤中殘留之有效矽量等收支估計可以推測所施有效矽量之約60%，已在土壤中被固定或吸著，變爲不易被pH4.0的規定1N溶液萃取的形態。
由以上結果可見矽酸爐渣之增產效果非常顯著。迄第10~13作爲止矽酸爐渣之連用雖沒有繼續增高其增產效果趨勢，惟一旦停止施用其增產效果却會顯著減低，故爲維持較高之土壤肥力水準，矽酸爐渣之繼續施用可謂必要，並以每次施用量較少但繼續施用者較一次施用多量，但停施甚久者有效。實用上，缺矽的稻田，如能於每年第一期作繼續施用，每公頃約1.5~2公噸矽酸爐渣將甚適當。

並列摘要

Field experiments have been carried out island-wide at 9 paddy locations on acid soils for 5 years (10 crops) using 3 treatments (1) check; no siliceous slag applied, (2) siliceous slag applied at the rate of 1.5t/ha/crop, and (3) siliceous slag applied at the rate of 3t/ha/crop. Nitrogen, phosphate and potash were amply applied to all of the test plots following the stantard recommended method. A randomized block design with two replications was adopted as the experimental procedure.
Beginning with the 7th crop, the plots with treatment (2) and (3) were each divided into two. One half of the plots received continuous siliceous slag applications while on the other, the application was interrupted, so that both the residual effect and the effect of continuous application could be observed.
Another experiment with and without the application of straw (0 and 5t/ha/crop, respectively) as primary treatment, and with and without siliceous slag (0 and 2t/ha/crop, respectively) as subtreatment was also conducted at one location for 61/2 years (13 crops) Application of siliceous slag on half of these pltos was also interrupted beginning with the 7th crop for the same reason as above.
The results may be summarised as follows
1. The yield responses to the slag application were generally high except at the beginning when the effect of slag seemed to be slightly lower. The yield increases in the plots with continuous slag applications of 1.5 and 3t/ha/crop fluctuated in the ranges of 5-15 and 8-20%, respectively during the experimental period (Fig. 2 & 3). When crop yields were high, as represented by the check plot yield, response to the slag application was low, and vice versa. This means that there was a generally negative relationship between check plot yield and slag application response. (Table 3 & 4, and Fig. 4). Thus, these experiments do not yet give any clear indication that the slag has any cumulative effect on the soil fertility (either positively or negatively) following continuous applications.
2. The residual effect of the slag was very significant soon after the interruption. Despite the previously continuous application of siliceous slag, the interruption resulted in an immediate decrease in the percentage of yield' increase compared to the plot with continuous application. Furthermore, the difference the grew greater as time lapsed after the interruption.
The residual effect remained higher in the plot where slag had been applied at the rate of 3t/ha/crop than in the plot where it had been applied at the rate of 1.5t/ha/crop.
3. The continuous application of 1.5 and 3t/ha/crop of siliceous slag on the first 7 crops resulted in total increases averaging 0.4 and 0.8 unit soil pH, and 130 and 300ppm of available silica in the soil, respectively. These levels were maintained in the plot with the continuous application during the following crops, while they declined significantly once the application was interrupted. (Table 5 and Fig. 5)
About 60% of the sillica was either absorbed or disslpated in the soil, and was not readily extractable by the pH 4.0 acetate buffer solution.
(Table 8)
4. All of the above would seem to indicate that a continuous application of silice ous slag is beneficial for maintaining an increased level of soil fertility, since once the application is interrupted, the silica level in the soil, as well as the yield, decline. A lower, but continuous application would seem to be more effective than a higher rate of application which is interrupted for a long time. In prtacice, a continuous application at the rate of about 2t/ha on the first rice crop in each year can be recommended for the acid soils deficient in available silica.