EFFECTS OF HIGH RATES OF CHEMICAL FERTILIZER AND BARNYARD MANURE ON YIELD AND MOISTURE USE OF SIX SUCCESSIVE BARLEY CROPS GROWN ON THREE GRAY LUVISOLIC SOILS

Abstract

High rates of chemical fertilizer and barnyard manure were applied separately and together to barley (Hordeum vulgare L.) grown on three Gray Luvisolic soils for 6 successive yr. The fertilizers were applied annually with the N–P–K rates greater than 110–50–40 kg/ha. The manure was applied initially at 134 tonnes/ha and at 150 tonnes/ha before the fifth crop. Moisture use by the barley was measured for the last five crops. Average yields of barley were 1,530, 3,270 and 3,950 kg/ha for the nil, manure and fertilizer treatments, respectively. The manure + fertilizer treatment gave little or no further increase in yield over the fertilizer treatment. Efficiency of moisture use was generally more than doubled by the fertilizer and fertilizer + manure treatments. These treatments also greatly increased the use of soil moisture reserves, the greatest increase being for Beryl fine sandy loam, followed by Hazelmere loam and the least for Nampa clay loam. Soil moisture reserves at harvest time were depleted more under the fertility treatments than under the control plots. However, by the following spring, soil moisture reserves were nearly equal under the different plots having been replenished by fall and winter precipitation. These results show that on stubble land, moisture restricted yields much less than nutrients did and, on that basis, continuous cropping of Gray Luvisolic soils is discussed.