Evaluasi Status Hara Kalium Pada Tanah Sawah di Pulau Jawa

Abstract

It was reported in 1975 by Research Centre for Soil and Agroclimate that the content of potassium (K) determined by HCl 25 % on paddy field in Java island ranged from low to high. Another report published in 2000 by above institution showed that most of paddy field in eighteen (18) provinces in Indonesia contained K in high status determined by HCl 25%, and most of them were located in Java island. The high content of K in paddy field especially in Java Island was due to application of K fertilizer in long periode. This long periode of K fertilizer application was supposed to cause unbalance soil nutrients status. The latter was one of the factors causing the leveling off in rice production. Therefore it is necessary to reevaluate the status of K in Java island to have good management and to maintain high rice production. The objectives of this research were to evaluate exchangeable K status on paddy field in Java island determined by 1 N NH4OAc pH 7, non exchangeable K and total K. Moreover the effect of location and soil order to the amount of exchangeable K, non exchangeable K and total K were also evaluated. Soil samples amounted to 23 samples from paddy field in Java island were collected. It consisted of 7 samples from West Java, 11 samples from Central Java and 5 samples from East java. Those soil samples were analysed for exchangeable K, non exchangeable K and total K. The results showed the content of exchangeable K, non exchangeable K and total K varied among locations and soil orders. For exchangeable K status in those samples varied from low to high status judged by criteria published by Research Centre for Soil and Agroclimate (1992). From 23 locations in Java Island, 9 locations were low status, 8 locations were medium status and 6 locations were high status. West Java consisted of 7 locations. From 7 locations in West Java, 2 locations were low status, 3 locations were medium status and 2 locations were high status. Central Java consisted of 11 locations. From 11 locations in Central Java, 4 locations were low status, 4 locations were medium status and 3 locations were high status. East java consisted of 5 locations. From 5 locations in East Java, 3 locations were low status, 1 location was medium status and 1 location was high status. Comparison of the mean values of exchangeable K among the provinces showed that all the provinces were in medium status. Locations and soil orders did not statistically significantly affected the differences of exchangeable K, non exchangeable and total K values. However this research revealed that Central Java contained the highest mean value of exchageable K and non exchangeable K and East Java contained the lowest mean values of those forms of K. As for total K, West Java contained the highest value of total K and East Java contained the lowest value of total K. Inceptisols contained the highest mean values of exchangeable K and total K, while Vertisols contained the highest mean values of non exchangeable K. Ultisols contained the lowest mean values of exchnageable K, non exchangeable K and total K. These results suggested that the amount of K fertilizer applied on the farmer fields in Java island were not uniform indicated by high standar deviation within the samples of one province. Moreover this research revealed that non exchangeable K ranged from low to high so the different K fertilization management among the provinces should be implemented.