On-farm Trials on the Dry Matter Yield Response of Pangola Grass (<I>Digitaria decumbens</I>) to Fertilizer Application

Abstract

Two on-farm trials were conducted in the paddy fields of the farmers at Chaiprakarn and Samkamphaeng districts, Chiang Mai province in order to study the responses of pangola grass to fertilizer application rates on dry matter yield. There were 7 farmers' fields at Chaiprakarn and 5 fields at Samkamphaeng. The experimental design for each district was RCB using each farmer field as one block. Five fertilizer application rates used in each farmer field were as follows : 1) recommended rate of Department of Life Stock (R-rate) using 25 kg of 15-15-15 and 20 kg of urea/rai, 2) farmer rate (F-rate) using urea within the range of 0-20 kg/rai depended on each farmer, 3) application rate according to soil test and crop removal of N, P and K (ST-rate), 4) ST-rate plus lime application at the rate of 1,000 kg/rai (STL-rate), and 5) ST-rate plus cow manure application at the rate of 3,000 kg/rai/year (STM-rate). The soils from all tested farmers' fields were extremely acidic with high levels of available P and exchangeable K. Thus, only urea at the rate of 17 kg/rai/harvest was used in the ST-rate. Results found that pangola grass from both areas responded significantly to fertilizer application rates, but the cutting period in which the grass had significant responses and the responsive pattern in each area were different. In both areas, at each cutting period in which the significant responses were found, the R-rate produced highest dry matter yield and differed significantly from the other rates. At Sankammphaeng area, STL and STM rates were significantly better than ST-rate for dry matter yield at some cutting periods. Though the R-rate provided the total dry matter yield from the four cuttings more than the ST-rates at both areas, but the use of ST-rates produced 2 times more dry matter per unit weight of primary nutrients in the applied fertilizer than the R-rate.