土壤肥力診斷在水稻精準施肥管理之應用

Abstract

本研究依據現行水田土壤肥力診斷推薦施肥技術，設置氮、磷、鉀肥不同用量處理，並設置氮肥高量及磷鉀肥足量施用之農家慣用量區為對照，探討不同肥料用量處理水稻各生育時期、階段之乾物累積及要素吸收量之變化及產量之差異。結果顯示：氮素施用210kg / ha的對照區較依現行推薦用量130kg/ha的各處理區，其產量增加約18 % ，推薦量區與對照區的乾物質產量相比較，抽穗期時明顯較少，達統計上的差異。較低磷肥用量區（P2O515 kg /ha ）水稻在幼穗形成期至抽穗期之乾物累積量明顯較其他處理少，而氮、磷、鉀要素之吸收量此時也明顯較低，甚至抽穗期至收穫期之間之吸收量也較其他處理低，而高量肥料區之水稻在抽穗期時已生產大量乾物及吸收多量氮、磷及鉀素，因而在抽穗期以後之增加量也明顯較少。水稻幼穗形成期植株之磷濃度與單位面積的穀粒數呈顯著正相關，惟其對產量的影響幅度較少，不似氮肥具有明顯的增產效應。稻穀產量與幼穗形成期植株氮含量呈極顯著正相關，顯示氮肥的影響甚大，且明顯高於磷鉀肥的影響。應用土壤肥力診斷，來推薦磷肥用量係依據前人研究之成果，為代表各種條件之平均值，而本期作之氮條件有利於水稻生長及乾物生產，因生長量增加故對營養元素的需求也增加，因依現行土壤磷肥力診斷具較高有效磷含量，而施用較低量磷肥之處理區，水稻明顯呈現磷肥供應不足，影響水稻生育及稻穀生產。另，磷、鉀要素對水稻產量之影響明顯較氮素小。 Designed according to recommendation of current soil fertility diagnosis, different rates of fertilizer trial with conventional farms¡¦ use as check is conducted to investigate yield difference and variation of dry matter accumulation and nutrients uptake various growth phases of rice. The result indicated yield in N 130 kg/ha treatment responded lower than check (N 210 kg/ha) by 18 %, and during heading stage dry matter production of recommended N 130 kg/ha also significantly less than that of check. The dry matter accumulated and mineral N,P,K,. and uptake during panicle initiation stage to maturity stage of rice grown in the lowest P fertilizer rates plot (P2O5 15 kg/ha) were lower than other treatments. P content of rice at panicle initiation stage had significantly positive relation with grain number per unit area, but its¡¦ effect was less than the effect of N. Grain yield had significantly positive relation with N content of rice at panicle initiation stage. Derived from soil fertility diagnosis and reference experimental results, recommended rate of P205 represent an average of various conditions. As climate condition in this crop favored rice growth, nutrient demand accordingly raised for dry matter production. Thus, low P205 treatment plot diagnosed as containing abundant soil available P, was observed insufficient P supply to rice influencing its growth and grain production. Besides, influences of P and K contributing to rice yield were apparently much less than that of N.