Synchronization of nitrogen release from prunings of legume trees in hedgerow intercropping with crop demand for nitrogen : I. recovery of nitrogen released from the prunings by maize

Inglés. Decomposition and nitrogen mineralization of prunings from five species of legume hedgerow trees (Calliandra calothyrsus, Peltophorum dasyrrachis, Leucaena leucocephala, Gliricidia sepium, and Flemingia congesta) in relation to the pruning quality and methods of pruning application were studied in a laboratory and in the field. Quality of the prunings was determined by measuring polyphenol content, lignin content, C/N ratio, and protein-binding capacity of polyphenols in the prunings. N mineralization of the prunings was tested upon application to the soil in a laboratory under controlled leaching and non-leaching conditions over the period of 14 weeks. The absolute decomposition rates of the prunings was measured using litterbags placed randomly on the soil surface or incorporated in the soil in the field over the period of 8 weeks. The N release rate constant (k) was calculated using a single-pool model of y = exp (-k.t.). The results showed that the contribution of decomposing pruning materials to the soil was not only associated with their quality and with the leaching conditions, but also with the method of application of the prunings in the field. The decomposition and N release rate constants of prunings declined in the order of Gliricidia Leucaena Flemingia Calliandra Peltophorum for all experiments carried out. The effect of quality of N release from legume prunings was modified by leaching conditions. Where there was no leaching, the protein-binding capacity of polyphenols in the prunings can play an important role in controlling the rate of N release. Under leaching conditions, the combined (lignin + polyphenol)/N ratio became an important quality factor in affecting the N release. The amounts of N released from the prunings placed on the soil surface were much smaller than those released from the incorporated prunings

Indonesio. Dekomposisi dan mineralisasi nitrogen dari bahan pangkasan lima spesies pohon leguminosa (Calliandra calothyrsus, Peltophorum dasyrrachis, Leucaena leucocephala, Gliricidia sepium, dan Flemingia congesta), dalam hubungannya dengan kualitas pangkasan dan metode aplikasi bahan pangkasan dipelajari di laboratorium dan di lapangan. Kualitas bahan pangkasan ditetapkan dengan menganalisis kandungan polifenol, kandungan lignin, kandungan nitrogen, rasio C/N dan kapasitas peningkatan protein oleh polifenol dalam bahan pangkasan. Mineralisasi N dari pangkasan dalam tanah diuji di laboratorium pada kondisi tercuci dan tidak tercuci selama 14 minggu. Kecepatan dekomposisi bahan pangkasan diamati dengan menggunakan kantong serasah ('litterbag') yang ditempatkan secara acak pada permukaan tanah dan dibenamkan dalam tanah di lapangan selama 8 minggu. Konstanta kecepatan pelepasan N (k) dihitung dengan menggunakan persamaan eksponensial y = exp (-k.t.). Hasil penelitian menunjukkan bahwa kontribusi N bahan pangkasan terhadap tanah tidak hanya berkaitan dengan kualitas bahan pangkasan dan kondisi pencucian, tetapi juga berkaitan dengan metode aplikasi bahan pangkasan di lapangan. Konstanta kecepatan dekomposisi dan mineralisasi N bahan pangkasan secara berturutan adalah: Gliricidia Leucaena Flemingia Calliandra Peltophorum untuk semua percobaan. Pengaruh kualitas terhadap pelepasan N dari bahan pangkasan dimodifikasi oleh kondisi pencucian. Pada kondisi tercuci, kapasitas pengikatan protein oleh polifenol dalam bahan pangkasan berperan penting dalam pengendalian kecepatan pelepasan N. Pada kondisi tercuci, kombinasi rasio (lignin + polifenol)/N menjadi parameter kualitas yang penting yang mempengaruhi pelepasan N. Jumlah N yang dilepaskan dari bahan pangkasan yang diletakkan di permukaan tanah jauh lebih kecil jika dibandingkan dengan jumlah N yang dilepaskan dari bahan pangkasan yang dibenamkan dalam tanah