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STATUS FOSFOR TERSEDIA DAN RETENSI

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STATUS FOSFOR TERSEDIA DAN RETENSI
STATUS FOSFOR TERSEDIA DAN RETENSI FOSFOR DALAM TANAH
SELAMA MASA PERTANAMAN PADI TANAM PINDAH
DI SUMATERA UTARA
Ali Jamil
Balai Pengkajian Teknologi Pertanian Sumatera Utara
Abstrak
Status kesuburan tanah yang rendah terdapat pada hampir semua lahan sawah tadah
hujan karena pertanaman terus menerus dengan sedikit atau tidak ada penggantian hara
dan/atau kesuburan tanah yang rendah secara alami. Penelitian bertujuan untuk
mengevaluasi dinamika berbagai sifat tanah selama pertumbuhan padi dengan sIstem
tanam pindah sebagai pengaruh penggunaan pupuk fosfor dan pupuk kandang sapi pada
lahan sawah tadah hujan di Kabupaten Langkat, Sumatera Utara. Percobaan telah
dilakukan sejak bulan Juni hingga Oktober, 2004. Perlakuan terdiri dari kombinasi 0; 30;
60; dan 90 kg P2O5 ha-1 dan 0; 3; dan 6 ton pupuk kandang sapi per ha. Perlakuan
disusun berdasarkan Rancangan Acak Kelompok dalam bentuk faktorial dengan
beberapa sifat tanah sebagai parameter yang diukur dalam penelitian ini. Hasil penelitian
menunjukkan bahwa, penggunaan pupuk fosfor dan pupuk kandang sapi nyata
meningkatkan ketersediaan hara fosfor tersedia, namun menurunkan nilai retensi fosfor
tanah. Disimpulkan bahwa, kedua perlakuan baik pemakaian fosfor maupun pupuk
kandang sapi berpengaruh positif terhadap upaya perbaikan kesuburan tanah,
khususnya pada lahan sawah tadah hujan di Sumatera Utara. Secara umum pemberian
90 kg P2O5 ha-1 dan 6 ton.ha-1 pupuk kandang sapi memberikan nilai kandungan hara
paling besar dibandingkan perlakuan lainnya.
Kata kunci: Status, fosfor tersedia, retensi fosfor, pertanaman, padi tanam pindah,
Sumatera Utara
Abstract
Low soil fertility status is a general issue of rainfed areas due to either continued
cultivation with little or no nutrient replenishment and/or to inherently low soil fertility. The
purpose of study was to evaluate soil characteristics dynamic during transplanted rice
growth period in Langkat District, North Sumatra as affected by phosphorus fertilizer and
cow manure application in to rainfed lowland rice particularly in Langkat District, North
Sumatra. The experiment was conducted from June to October 2004. Treatments
involved a combination of 0, 30, 60, and 90 kg.ha-1 of P2O5 and 0, 3, and 6 t.ha-1 of cow
manure. Treatments were laid in a factorial RCBD with 3 replications. Results showed
that application of both phosphorus and organic matter significantly increased available
phosphorus, however, significantly decreased soil phosphorus retention. Based on the
results obtained, were concluded that both phosphorus and cow manure have positive
effect to improve soil fertility status, especially under rainfed lowlands rice, and generally
application of 90 kg.ha-1 of P2O5 and 6 t.ha-1 of cow manure had greater effect on soil
nutrient content compared to other treatments.
Keywords: Status, available phosphorus, phosphorus retention, cultivation, transplanted
rice, North Sumatra
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