Development of efficient irrigation schedules and soil salinity monitoring system in productive green arid lands

本研究的目的是提出有效的灌溉制度和发展新的土壤盐分监测系统，假设生产绿色干旱土地条件。研究结果如下：（1）通过对集水效率80%、日灌溉间隔、设计灌溉间隔、灌溉面积150 ~ 300 m <@D12@>D1条件下4 ~ 22 a灌溉周期的模拟结果的讨论，提出了水箱灌溉系统的灌溉制度。(2)将含有<@D122@> D1 Na的氯化钠溶液加入大麦沙丘沙中，以追踪Na在土壤和植物中的迁移。采用具有数字信息和高灵敏度的成像板（IP）代替X线胶片。结果表明，IP比X射线胶片更能反映Na在土壤中的运动和Na在植物体内的迁移。(3)几种介质型土壤水分探头的测量精度（Ⅰ）电磁波法 ...更多信息 e，（ii）共振现象，（iii）复介电常数，（iv）时域反射法和（v）振幅域反射法进行了评价，使用盐砂。讨论了盐分浓度对土壤含水量测定的影响。基于幅域反射法的四平行杆场式介质土壤水分仪的测量精度在± ±（）SY. [）0.01 cm<@D13@>D1/cm<@D13@>D1和（）SY. ±.（1）在低、高水位区，D_1/D_1分别为0.02 cm<@D13 @>/cm<@D13@>。与（）至30，000 ppm氯化钠溶液范围内的其他土壤湿度计相比，该仪器受盐浓度对湿度测量的影响很小。(4)为了监测土壤中的溶质运移，四电极盐度探头被缩小，以尽量减少任何干扰的运输过程。使用四个探针测定了饱和和非饱和水流的分散系数D，用于常规鸟取沙丘砂（2%粘土含量）和不含粘土的洗砂。饱和流的分散性几乎是恒定的（0.1厘米），无论孔隙水速度，v，两种砂。非饱和流的弥散系数大于饱和流的弥散系数（>0.3cm）。规则沙丘沙的D值大于冲刷沙，特别是在含水量较低（> 1cm）时。(5)根据实验和野外观测结果，提出了一种新的基于光谱反射率的植被覆盖指数。在由沙、盐（NaCl）和植被（草皮）组成的模型表面上验证了该方法的适用性。实验中推导出了利用光谱反射率估算沙覆盖率和盐覆盖率的方法。提出了利用光谱反射率诊断植被水盐胁迫的方法。少

The aims of this research project are to propose the efficient irrigation schedules and to develope new soil salinity monitoring system, assuming productive green arid land conditions. The results are as follows ; (1) Irrigation scheduling for tank irrigation system was proposed by discussing simulation results estimated under conditions of water harvest efficiency of 80%, daily irrigation interval, design irrigation interval, irrigated areas of 150 - 300m<@D12@>D1 during irrigation periods of 4 - 22 years. (2) The sodium chloride solution containing <@D122@>D1Na was added to barley-grown dune sand in order to trace the movement of Na in the soil and plants. The imaging plate (IP) which has digital information and high sensitivity was used instead of X-ray film. It was found that the IP could trace the movement of Na in the soil and the translocation of Na in plants than the X-ray film. (3) The measuring precision of some dielectric soil moisture probes based on (i) electromagnetic wav … More e, (ii) resonance phenomenon, (iii) complex dielectric constant, (iv) time-domain reflectometry and (v) amplitude domain reflectometry was evaluated using salty sand. The influence of salt concentration on the measurement of soil water content was discussed. A field-type dielectric soil moisture prove with four parallel rods based on amplitude domain reflectometry had the measuring precision within (]SY.+-。[)0.01 cm<@D13@>D1/cm<@D13@>D1 and (]SY.+-。[)0.02 cm<@D13@>D1/cm<@D13@>D1 in the low and high water range, respectively. The gauge had small influence of salt concentration on moisture measurement compared with other soil moisture gauges in the range ()to 30,000 ppm of NaCl solution. (4) In order to monitor solute transport in soil, four-electrode salinity probes were downsized to minimize any disturbances of the transport processes. The dispersion coefficients, D,for a regular Tottori dune sand (2 % clay content) and a washed sand without clay were determined for saturated and unsaturated flows using the four probes. The dispersivity for saturated flow is almost constant (0.1 cm) regardless of the pore water velocity, v, for both sands. For unsaturated flow the dispersivity is greater (>0.3cm) than forsaturated flow. The regular dune sand has greater D than for the washed sand especially for lower water content (> 1cm). (5) New vegetation cover index (VCI) using spectral reflectances was derived from the results of the experiments and field observation. It's applicability was confirmed on the model surfaces which were composed of sand, salt (NaCl) and vegetation (turf). The methods to evaluate the sand cover ratio and salt cover ratio using spectral reflectances were derived in the experiment. The method to diagnose the water and salt stresses of vegetation using spectral reflectances are also proposed. Less