Evaluation of status and micro nutrient fertilization for cane at paddy field continuously fertilized with ZA on Aluvial land (Thypic Tropaquept) Pekalongan

English. The concentration of sulphate and sulphide in soil relates to the availability of micro nutrients as well as soil acidity. High accumulation of sulphate causes low soil pH and low micro nutrients availability. Field experiment to evaluate status and fertilization of micro nutrient on cane at paddy field that continuously fertilized with ammonium sulphate on an Aluvial land (Thypic Tropaquept) of Pekalongan, had been executed through land profile monitoring. There were 13 treatments, i.e. 1. 0 kg Cu; 2. 4 kg Zn; 3. 8 kg Zn; 4. 12 kg Zn; 5. 4 kg Cu; 6. 8 kg Cu; 7. 12 kg Cu; 8. 4 kg Mn; 9. 8 kg Mn; 10. 12 kg Mn; 11. 4 kg Fe; 12. 8 kg Fe and 12 kg Fe per hectare. The treatments were arranged on a Randomized Block Design with 3 replications. The result showed that on soil body the concentration of micro nutrient decreases from top layer into base layer along with concentration increment of sulphate from top layer into base layer. Addition Hidrogen Peroxide (H2O2) on the soil before chemical analysis in fact improves concentration of micro nutrient element of Fe, Mn, Cu and Zn sulphate, presumably from oxidated sulphide salts. Micro nutrient fertilizing significantly influence diameter and weight of cane, sucrose content and crystal of sugar. Compared to infertilized treatment, addition of Zn, Mn, Fe and Cu was able to improve sugar yield by 34, 24, 23 and 10 percent respectively

unknown. Konsentrasi ion sulfat dan sulfida dalam tanah berhubungan dengan ketersediaan hara mikro dan kemasaman tanah. Akumulasi sulfat di dalam tanah dapat berasal dari penambahan pupuk berkadar sulfat tinggi yang dilakukan secara terus-menerus. Hal tersebut dapat berdampak menurunkan ketersediaan hara mikro dan pH tanah. Percobaan lapangan yang bertujuan untuk mengevaluasi status dan pumupukan hara mikro pada tebu lahan sawah yang terus-menerus dipupuk ZA di tanah Aluvial (Thypic Tropaquept) Pekalongan telah dilaksanakan pada musim tanam 1992/1993. Evaluasi status hara dilakukan melalui pengamatan profil tanah sedangkan percobaan lapang pemupukan hara mikro diujikan 13 perlakuan yaitu 1. 0 kg Cu; 2. 4 kg Zn; 3. 8 kg Zn; 4. 12 kg kg Zn; 5. 4 kg Cu; 6. 8 kg Cu; 7. 12 kg Cu; 8. 4 kg Mn; 9. 8 kg Mn; 10. 12 kg Mn; 11. 4 kg Fe; 12. 8 kg Fe dan 12 kg Fe tiap hektar. Perlakuan disusun dalam Rancangan Acak Kelompok dengan 3 ulangan. Hasil penelitian menunjukkan bahwa pada tubuh tanah konsentrasi hara mikro menurun dari lapisan atas ke lapisan bawah sejalan dengan peningkatan konsentrasi sulfat pada tanah tersebut. Penambahan larutan Hidrogen Peroksida (H2O2) pada tanah sebelum analisis kimia ternyata meningkatkan konsentrasi hara mikro Fe, Mn, Cu dan Zn serta sulfat. Penambahan hara-hara tersebut diduga berasal dari garam-garam sulfida yang teroksidasi. Pemupukan hara mikro berpengaruh nyata terhadap diameter batang tebu, bobot tebu, rendeman dan kristal gula. Perlakuan pemupukan jenis mikro Zn, Mn, Fe dan Cu mampu meningkatkan kristal gula berturut-turut sebesar 34, 24, 23 dan 10 persen dibanding tanpa perlakuan pemupukan