澎湖縣土壤肥力與高粱磷鉀效應之關係

Fertility Status and Response of Sorghum to PK Fertilizers in the Soils of Pescadores Islands

林家棻(Char-Fen Lin)

《中華農業研究》 30卷3期 (1981/09) Pp. 261-269

https://doi.org/10.29951/JARC.198109.0006

摘要

澎湖縣土壤之母質主要爲玄武岩，經選取三種土鏖包括沖崩積土，殘積土及上層沖崩積土下層殘積土，在24處舉行高粱磷鉀效應田間試驗，從供試土壤陸質顯示殘積土之土層厚度多在90cm上下，其他兩種土壤則變化較大，從30cm至90cm不等。pH均在7.7至8.1間，表土含砂量多在70%以上，有機物含量高者僅1.5%，低者不及0.5%，但土壤陽離子交換能量高者可達30me/100gm，低者不及3me/100gm，兩者相差達10倍。土壤中Bray P1含量甚低，鮮有超出1ppm P，但交換性鉀則頗高，多在100ppm K以上，一般言之，冲崩積土肥力較高，殘積土較低，上層沖崩積土下層殘積土居中，各種土壤上所得高梁平均收量之高低，亦有此煩向。
土壤中Bray P1或Olsen P各與高梁磷肥效應有關，但其相關係數僅在0.5上下，而土壤中交換性鉀，Mehlich K及Olsen K則與高粱鉀肥效應無關。經利用程式計算機，將土壤其他特性因子，參予磷鉀校正公式中，求出最適合之複相關模式爲：
Ŷ1=2.535a-0.1393a^2-79.18c^2+42.58c^2+5.819ac-43.96b+430.9………(1)
Ŷ2=1.284a+0.124a^2+0.406d+0.0002d^2+0.034ad-97.15b+828.6………(2)
式中Y1及Y2各指估計無磷區(P0/P×100)及無鉀區(K0/K×100)之高梁收量百分率，a=clay%，b=pH，c=Bray P1 ppm，d=交換性K ppm，方程式(1)及(2)兩式所得複相關係數各爲0.7735及0.8362，均達1%顯著平準，確有改進功效，文中並檢討在一定範圍內，土壤pH，粘土含量以及土壤有效態磷鉀含量與無磷區或無鉀區高粱收量百分率估計值之關係。

並列摘要

To clarify the response of sorghum to PK fertilizers, twenty-four field trials involved five treatments with four replications in a randomized block were conducted on soils derived from weathering basalt rock on the Pescadores Islands. These soils may be divided into three groups: wind eroded soil, residual soil, and upper eroded soil with residual soil underneath.
Judging from the fertility status of the soils studied, it indicated that the depth of solum of residual soils was rather uniform at 90 cm or so. However a wide variation in solum (30-90cm) was found in the other two soils. The ranges of soil pH and the content of organic matter were at 7.7-8.1 and 0.5-1.5%, respectively. Almost all soils contain more than 70% of sand in the surface soils. Although these soils contain abundence of sand and low level of organic matter, there was a wide range in cation exchange capacity (3-33 me/ 100 gm). The available phosphorus index measured by Bray method (0.025N HCl-0.03N NH4F) was extremely low, usually less than 1 ppm P. On the other hand, a wide range in exchangeable K(54-538 ppm K) was found in the surface soils. In general, the fertility level of these soils was ranked in the following order: wind eroded soil, upper eroded soil with residual soil underneath and residual soil. Consequently, the average yields of sorghum obtained from wind eroded soils were higher than those from the other two soils.
The relationship between percentage yield and soil PK tests were improved by participating the constituents of soil pH and clay in the calibration equation. The fitting models of multiple regression equation were found as follows
Y1=2.535a-0.1393a^2-79.18c+42.58c^2+5.819ac-43.96b+430.9………(1)
Y2=1.284a±0.124a^2+0.406d+0.0002d^2+0.034ad-97.15b+828.6………(2)
where Y1 refers to the predicated percentage yield from P0/P ×100 and Y2 from K0/K×100. From the equations, it indicated that at the soil pH lower than 7.7, mostly no profitable return will be obtained by PK-application except in the case where soil available P was lower than 0.2 ppm. However, when soil pH was greater than 8.1, the responses of sorghum to PK fertilizers will be depended on the contents of clay and levels of soil PK. The predicated percentage yield responses for a range of combination of the test values were discussed in the paper.