EFFECT OF IRRIGATION FREQUENCY ON SOIL WATER CONTENT AND SOLUTE MOVEMENT UNDER MAIZE CROPIN CALCAREOUS SOILS

摘要

A lysimeter study was conducted during 1997-2000 at green house of Soil Chemistry Section, Ayub Agricultural Research Institute, Faisalabad to assess the effect of varying irrigation frequencies on soil moisture contents, leaching of solutes, yield, water use efficiency (WUE) and N uptake by maize (Zea mays L) in fully controlled and monitored conditions. Three irrigation levels 3 (I_1, 4.5 (I_2) and 6 (I_3) acre inches were applied in permanently constructed cemented lysimeters having dimensions 4 X4 X 4 feet. Recommended dose of N, P_2O_5 and K_2O @ 75-60-60 kg ha~(-1) was applied in form of Urea, SSP and SOP respectively. Soil samples were collected before each irrigation to determine the actual moisture contents and solute (NO_3~- & NO_2~-) movement at various profile depths (i.e.0-15, 15-30, 30-60, 60-90, 90-120 cm). The Results revealed that after each irrigation no leachate was obtained at the bottom of each lysimeter which clearly indicated that there is no any pollution/leaching threat from agricultural chemicals like NO_3. Soil analysis data showed that moisture contents and NO_3-N concentration in profiles increased with increasing depths but this increase is not enough to leach down the water through the soil profile. Maize was harvested 61 days after transplanting. Fodder yield and N uptake of maize was significantly affected by irrigation levels during 1997-98 and 1998-99. WUE of the crop was statistically non-significant during 1997-98 but during 1998-99 significantly higher WUE was recorded at irrigation frequencies of I_1 and I_2 than I_3.