Hisao Anyoji

Effects of deficit irrigation and fertilizer use on vegetative growth of drip irrigated cherry trees

ABSTRACT The effects of deficit irrigation and fertilizer use under drip irrigation (DI), on vegetative growth of mature cherry trees were studied in two field experiments. Treatments for the assessment of deficit irrigation consisted of two drip line arrays: double drip lines (T1) and loop (T2) as main treatments. Three irrigation levels: irrigation at 100% of crop evapotranspiration (ETc or I1), 75% ETc or I2, and 50% ETc or I3, constituted the sub-treatments. To assess soil fertility practices, the main treatments consisted of T1 and single drip line (T3) arrays; sub-treatments were two fertilizer regimes: basic fertilizer recommendation plus 0.5 m3 sheep manure per tree (F1) and basic fertilizer recommendation plus 1300 g potassium sulfate, 350 g of zinc (Zn), 140 g of iron (Fe), and 600 g ammonium phosphate (F2). Total irrigation amount, which was applied routinely in control treatment (7466.7 m3ha− 1), was less than the crop water requirement (8764.5 m3 ha− 1). A significant correlation between both the length of young branches and canopy volume with annual applied irrigation water was observed. Mean canopy volume under T1 was 26.0 m3 tree− 1, which was significantly less than 28.6 m3 tree− 1 under T2. Water use efficiency (kg m− 3) was increased by water stress, but there was no significant yield reduction from I1 to I2. Concentration of Fe, phosphorus (P), potassium (K), and magnesium (Mg) in leaf samples increased with the use of double drip lines array compared to use of single drip line array and it was higher under F2 fertilizer level. The concentration of calcium (Ca) in leaf samples was higher than critical level in all treatments. We conclude that I2 irrigation level and F2 fertilizer management was the most efficient practice for cherry trees in the study area.

Application of unsteady flow analysis in designing a multiple outlets sprinkler irrigation system

A simplified method has been developed for designing and calculating sprinkling systems by cutting lines across laterals at points next to the first sprinkler with a view to divide the system into two separate parts; field and basic. Equations of lateral pressure heads were used to express the relationship between inlet pressure head and velocity of the flow pumped to laterals on the field part. The above equations were then used to set up calculating conditions for the Basic part by unsteady flow method in order to define head and discharge at downstream end of the pipe in the Basic part. The forward step method was used for determining distributions of the pressure head and the emitter discharge along each lateral. A calculating schema on computer has been carried out in order to apply the method to any sprinkling system. The procedure of analysis and calculation showed that this method is generally accurate, simple and rapid.

Interaction of Soil Water Content and Soil Solute Salinity under Drip Irrigation in Dune Field

Saline water use with drip irrigation system (DIS) has several advantages over other irrigation methods if managed properly. Variables affecting soil water content ( ew) and soil solute salinity (ECw), including irrigation regimes; pan evaporation (Id), Id·1.20 and Id·1.40 and crop growth stages e.g. development (DS), mid (MS), and late (LS) stages, were investigated at different radius from the emitter (lateral pipe) and 10 cm soil depth, where most part of the crop root was concentrated. The simultaneous distribution of water and solute under drip irrigation was measured using Time Domain Reflectometry (TDR) method. The results indicated that ew and ECw increased in the order Id>Id·1.20>Id·1.40 and LS>MS>DS. The maximum ew and minimum ECw coincided at 10 cm radius (r10) from emitter during all crop growing stages for all irrigation regimes. The same trend was noted for 20 cm radius from emitter (r20) during DS and MS of Id and Id·1.20, and during all of the crop growth stages for Id·1.40. Time elapsed since irrigation was terminated till ew increased to a maximum level at the r10, during DS, MS and LS was 3, 2 and 2 h respectively for Id and 4, 3, and 3 h for Id·1.20 and Id·1.40. It is therefore suggested that irrigation should commenced in different time before noon, in regard with the crop growth stages, so that maximum ew (minimum ECw) will coincide with maximum evapotranspiration (ETo). Interaction between ew and ECw for a given radius and different crop growing stages showed that the influence of ew on ECw was restricted to a small radius of about 0-20 cm from the emitter. Beyond this range, increase in ew did not significantly affected ECw. Id was concluded as a unrecommended irrigation regime for use of saline water. A distance of about 25 and 30 cm is recommended for 2 consecutive emitters on a lateral pipe under Id·1.20 and Id·1.40 respectively, to minimizing ECw.