水稻田紋溝灌溉之水分控制與節水效率分析

Analysis of Water Control and Water Saving Efficiency of Paddy Field Rill Irrigation

謝勝賢(Hsieh Sheng-Hsien)

指導教授 ： 葉一隆

國立屏東科技大學/工學院/土木工程系所/博士(2020年)

https://doi.org/10.6346/NPUST202000264

摘要

水稻是一種耗水量大的作物，如逢乾旱缺水，水資源越顯彌足珍貴，臺灣水稻灌溉漸採乾濕交替，而水稻田開溝灌溉為另一節水方法。本研究目的為比較水稻田溝灌和漫灌之不同灌溉方法，以建立溝灌與漫灌模式分析，並結合土壤之物理性結構與入滲關係，執行水分控制。試驗場分小田區滲漏計試驗與大田區試驗，滲漏區水稻栽培採用稻作強化體系，植株密度30 cm × 30 cm的少苗疏植，佈置田區開溝及未開溝三重複試驗；大田區使用傳統播種方式，灌溉區分溝灌及漫灌模式。
本研究所用大田區之土壤入滲率由試驗結果得知西區之基本入滲率為0.0237 mm/hr，東區則為0.0152 mm/hr，土壤屬砂質壤土，經設定土壤水分張力值為20 kPa時，其土壤含水量約為17 %。
依據小田區滲漏計試驗區試驗條件所建立之溝灌模式模擬結果用水效率為0.40 kg/m3，而實際平均用水效率為0.41 kg/m3；漫灌試區模擬之用水效率為0.32 kg/m3，實際平均用水效率為0.33 kg/m3，由分析可知水稻溝灌獲得較高用水效率。而以期作試驗結果比較，溝灌一期作實際用水效率為0.60 kg/m3，高於二期作實際用水效率0.35 kg/m3，此與歷年農政單位之統計報告，一期作產量高於二期作結果符合。
一期作溝灌模式於固定根系長與用水量情境時，模擬有效分糵數增加10 %，則模擬用水效率可以增加8 %，顯示水稻生育期間若增加有效分糵數相對可增加用水效率。當一期作溝灌模式固定有效分糵數與用水量時，模擬用水效率與根系長呈顯著正相關，顯示溝灌處理試區根系生長旺盛，有利於根系吸收水分及營養。
由小田區滲漏計試驗結果顯示溝灌具可靠度，於 107及108年一期作利用大田區進行溝灌與漫灌試驗驗證，由試驗結果顯示兩年度之溝灌較漫灌節水分別為8.3 %及27.3 %，表明水稻溝灌能提高用水效率之目的。另外由t檢定得知稻田開溝及未開溝之差異性，結果顯示開溝之穗長、穗重及稔實率具顯著性差異，而穎花數、稔實粒等均無顯著差異。

關鍵字

稻作強化栽培體系 ； 節水灌溉 ； 紋溝灌溉

並列摘要

Rice is a crop that consumes very large amounts of water which becomes particularly precious during times of drought and water shortage. In Taiwan, water conservation is aided by alternated wet and dry irrigation, with rill irrigation being another important water-saving method. The purpose of this study is to compare the rill and flooding rice field irrigation methods, conduct a model analysis for the two methods, and implement water control in combination with the relationship between infiltration and the physical structure of the soil. The testing for this study is divided into two separate lysimeter and field sites. The Rice cultivation on both sites adheres to the System of Rice Intensification (SRI), with seedlings planted at a 30 cm×30 cm density over three ditched and un-ditched experiments. On the field test site with clearly distinguished rill irrigation and flooding irrigation, on the other hand, traditional irrigation methods were used.
In this study, a feasible model of rice rill irrigation was established through experiments, with the analysis of soil infiltration in the field test site showing that the basic infiltration rate of the western and eastern areas were 0.0237 mm/hr and 0.0152 mm/hr respectively. The soil composition was sandy loam. When the soil moisture tension value was set to 20 kPa, the soil moisture content measured at about 17%.
Based on the established rill irrigation model, the simulated water efficiency is 0.40 kg/m3, while the actual average water efficiency is 0.41 kg/m3. On the simulated flooding irrigation test site, water efficiency measures at 0.32 kg/m3, while the actual average water efficiency is 0.33 kg/m3. The findings illustrate that rill irrigation achieves higher water efficiency. The sampling of the rill irrigation treatment at the lysimeter test site is divided into the spring rice crop and the summer rice crop. Compared with the higher water efficiency of 0.60 kg/m3 for the rill irrigation spring rice crop, the summer rice crop measures at a water efficiency of only 0.35 kg/m3. This is consistent to the statistical reports released by different Ministry of Agriculture divisions over the years that the output of spring rice is higher than summer rice.
In the spring rice crop on the rill irrigation lysimeter site, when root length and water consumption are fixed, the simulated effective fraction is increased by 10% while the simulated water efficiency is increased by 8%. This shows that increasing the effective fraction during the rice growth period can visibly increase water efficiency. When the spring rice crop rill irrigation pattern fixes the effective number of fraction points and water consumption, the simulated water efficiency is significantly correlated with root length. This shows that the root system grows vigorously in the rill irrigation treatment site, which is beneficial for the root system to absorb water and nutrients.
The re-regression results of the lysimeter test site showed the reliability of rill irrigation in comparison to flooding irrigation which were carried out in the field test site. In both 2018 and 2019, rill irrigation proved stronger than flooding irrigation with water saving of 8.3% and 27.3% respectively. In addition, the test difference between the rill and flooding rice fields showed that for rill rice fields, the ear length, ear weight, and stubble rate were significant factors, but that there was no significant difference in the number of spikelets and stubble seeds.

並列關鍵字

System of Rice Intensification ； Water Saving Irrigation ； Rill Irrigation

參考文獻

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