USING THE N-15 METHOD TO DETERMINE N-SOIL, N-GREEN MANURE, AND N-UREA AVAILABILITY AFTER SIX SEASONS IN AN ALLEY CROPPING SYSTEM

Nitrogen (N) is the most important nutrient for crop growth and production. This study was conducted to determine whether in each of six seasons and after these seasons the N-soil, N-green manure, N-green manure + urea, and N-urea is still available for crops. Upland rice and corn were planted successively for six seasons. In each season upland rice and corn were planted andapplied with N-fertilizers at rate of: control (0N), N1 (100% green manure), N2 (50% green manure + 50% urea), N3 (100% urea). N-15 labelled urea was added at each season to determine the A-value of the crops. In each seasons it was shown that crops used N-soil as well as N-fertilizer. With the increase of the availability of N-fertilizers the use of N-soil decrease and so couldpreserve N-soil. With preservation of N-soil it could be assumed that soil quality has increased. The N-15 method could be used to determine the availability at each fertilizer rate’s in each season and at the end of the sixth season

The use of 32P and 15N to Estimate Fertilizer Efficiency in Oil Palm

Oil palm has become an important commodity for Indonesia reaching an area of 2.6 million ha at the end of 1998. It is mostly cultivated in highly weathered acid soil usually Ultisols and Oxisols which are known for their low fertility, concerning the major nutrients like N and P. This study most conducted to search for the most active root-zone of oil palm and applied urea fertilizer at such soils to obtain high N-efficiency. Carrier free KH232PO4 solution was used to determine the active root-zone of oil palm by applying 32P around the plant in twenty holes. After the most active root-zone have been determined, urea in one, two and three splits were respectively applied at this zone. To estimate N-fertilizer efficiency of urea labelled 15N Ammonium Sulphate was used by adding them at the same amount of 16 g 15N plant-1. This study showed that the most active root-zone was found at a 1.5 m distance from the plant-stem and at 5 cm soil depth. For urea the highest N-efficiency was obtained from applying it  at  two splits. The use of 32P was able to distinguish several root zones: 1.5 m – 2.5 m from the plant-stem at a 5 cm and 15 cm soil depth. Urea placed at the most active root-zone, which was at a 1.5 m distance from the plant-stem and at a 5 cm depth in one, two, and three splits respectively showed difference N-efficiency. The highest N-efficiency of urea was obtained when applying it in two splits at the most active root-zone

Pengaruh Dosis Iramasi Sinar Y Terhadap Peningkatan Mn-Tersedia pada Beberapa Jenis Tanah. The effect of yRa ys irradiation on the available mn in several soil types.

INFLUENCE OF y IRRADIATION DOSES ON AVAILABLE-Mn IN SEVERAL SOILS. An experiment where three types of soils, namely, Andosol, Vertisol and Inceptisol have been irradiated by y rays was conducted. The purpose of the y rays irradiation was to sterilize the soil. After soil sterilization, the soils were innoculated with Bradyrhizobium, a microble able to fix N2 from the air and lives in simbiosis with soybean. Soybean was grown in the soils after inoculation. Observations were done for the available-Mn in soil and content in plants. Results showed that available-Mn in the soils in 50 kGy dose increased up to 3.7 times (5.3 ppm), 2.8 times (41.6 ppm) and 5.6 times (25 ppm) above the control for Andisol, Vertisol and Inceptisol respectively. Increase of available-Mn in the shoots were 1_54 times (80.66 ppm), 2.23 times (107.66 ppm), and 2.31 times (161.66 ppm) above the control for Andisol, Vertisol and Inceptisol respectively. For the roots the increased was 1.43 times (76.77 ppm), 1.43 times (101.09 ppm), and 2.17 times (212.33 ppm) above the control for Andisol, Vertisol and Inceptisol respectively Key Words : grays, mangaan, soybean, soil types. Percobaan menggunakan beberapa jenis tanah yaitu, Andisol, Vertisol dan Inceptisol yang diiradiasi sinar y dengan dosis iradiasi, 0, 30, 40 dan 50 kGy telah dilakukan. Tujuan iradiasi sinar y terhadap ketiga jenis tanah tersebut adalah untuk mensterilkan tanah dari mikroba yang dikandungnya. Setelah disterilkan ketiga jenis tanah tersebut diinokulasi dengan Bradyrhizobium yaitu mikroba penambat N2-udara yang bersimbiosis dengan tanaman kedelai. Setelah inokulasi dengan Bradyrhizobium ketiga jenis tanah tersebut ditanami kedelai varietas wilis. Pengamatan dilakukan terhadap kandungan Mn-tersedia dalam tanah dan kandungan Mn tanaman (tajuk dan aka:). Hasil yang diperoleh menunjukkan bahwa Mn-tersedia dalam tanah pada dosis 50 kGy meningkat 3.7 x (5.3 ppm). 2.8 x (41.6 ppm) dan 5.6 x (25 ppm) di atas kontrol berturut-turut untuk tanah Andisol, Vertisol dan Inceptisol. Untuk tanaman, Mn-tersedia naik 1.54 x (80.66 ppm), 2.23 x (107.66 ppm) dan 2.31 x (161.66 ppm) di atas kontrol untuk tajuk dan 1.43 x (76.77 ppm), 1.43 x (101.09 ppm) dan 2.17 x (212.33 ppm) untuk akar di atas kontrol berturut-turut untuk tanah Andisol, Vertisol and Inceptisol. Tidak ditemukan perbedaan pada kandungan Mn-tersedia pada tanah dan tanaman yang disebabkan perbedaan dosis iradiasi. Kata kunci : Sinar y, mangaan, kedelai, jenis tanah

PENGARUH PUPUK FOSFAT ALAM PADA TANAH MASAM TERHADAP PERTUMBUHAN JAGUNG SERTA SERAPAN N-ZA DAN N-UREA

Sebuah percobaan pot telah dilakukan di rumah kaca IPB Darmaga, bertujuan untuk mempelajari pengaruh pupuk fosfat alam (FA) pada tanah masam terhadap pertumbuhan tanaman jagung dan serapan N berasal dari ZA (N-Z) dan Urea (N-U). Jenis tanah yang digunakana adalah Typic Dystrudepts yang mempunyaisifat kimia dan fisik antara lain pH rendah dan kandungan pasir cukup tinggi. Tanah ini memiliki daya fiksasi terhadap unsur P yang tinggi sehingga kurang tersedia bagi tanaman. Oleh karena sifat tanah yang masam, maka ketika pupuk fosfat alamdiaplikasikan ke tanah tersebut akan lebih terlarut. Interaksinya dengan pupuk yang lain berpengaruh pada serapan N oleh tanaman. Tanaman percobaan yang digunakan adalah jagung varietas Pioneer. Tiga taraf pemupukan fosfat alam yaitu setara dengan 0, 50, dan 100 kg P2O5/ha dikombinasikan dengan pupuk ZA dan Urea masing-masing tiga taraf yaitu setara dengan 0, 50, dan 100 kg N/ha. ZA dan Urea bertanda 15N dengan atom ekses masing-masing sebesar 9,984 % dan 9,754 % diaplikasikan pada percobaan ini untuk mempelajari serapan N oleh tanaman jagung.Panen dilakukan pada saat pertumbuhan vegetatif maksimum yaitu 40 hari setelah tanam. Parameter yang diamati antara lain pertumbuhan tanaman dinyatakan dalam bobot kering (g), persentase N-total, serapan N-total (mg N/tanaman) serta persentase dan serapan N-berasal dari ZA dan Urea (% N-Z/U, serapan N-Z/U dinyatakan dalam mg N/tanaman). Hasil yang diperoleh menunjukkan bahwa baik pemberian N-ZA (NZ)maupun N-urea (N-U) dan P (FA) secara sendiri-sendiri maupun gabungan dapat mendorong pertumbuhan tanaman (bobot kering, g/tanaman) dan serapan N-total (mg N/tanaman) serta % atom ekses 15N. Dalam hal ini pupuk P (FA) memberikan pengaruh yang lebih dominan dibandingkan dengan pupuk N. Terdapat interaksiyang nyata antara pemberian N (pupuk ZA/Urea) dan P (fosfat alam) sehingga untuk memberikan kedua jenis pupuk tersebut secara bersamaan perlu dipertimbangkan adanya pemberian yang seimbang takarannya agar dapat diperoleh serapan N yangpaling optimal

THE USE OF 32 P AND 15 N TO ESTIMATE FERTILIZER EFFICIENCY IN OIL PALM

ABSTRACT THE USE OF 32 P AND 15 N TO ESTIMATE FERTILIZER EFFICIENCY IN OIL PALM. Oil palm has become an important commodity for Indonesia reaching an area of 2.6 million ha at the end of 1998. It is mostly cultivated in highly weathered acid soil usually Ultisols and Oxisols which are known for their low fertility, concerning the major nutrients like N and P. This study most conducted to search for the most active root-zone of oil palm and applied urea fertilizer at such soils to obtain high N-efficiency. Carrier free KH 2 32 PO 4 solution was used to determine the active root-zone of oil palm by applying 32 P around the plant in twenty holes. After the most active root-zone have been determined, urea in one, two and three splits were respectively applied at this zone. To estimate N-fertilizer efficiency of urea labelled 15 N Ammonium Sulphate was used by adding them at the same amount of 16 g 15 N plant -1 . This study showed that the most active root-zone was found at a 1.5 m distance from the plant-stem and at 5 cm soil depth. For urea the highest N-efficiency was obtained from applying it at two splits. The use of 32 P was able to distinguish several root zones: 1.5 m -2.5 m from the plant-stem at a 5 cm and 15 cm soil depth. Urea placed at the most active root-zone, which was at a 1.5 m distance from the plant-stem and at a 5 cm depth in one, two, and three splits respectively showed difference N-efficiency. The highest N-efficiency of urea was obtained when applying it in two splits at the most active root-zone

Using the n-15 method to determine n-soil, n-green manure, and n-urea availability after six seasons in an alley cropping system

USING THE N-15 METHOD TO DETERMINE N-SOIL, N-GREEN MANURE, AND N-UREA AVAILABILITY AFTER SIX SEASONS IN AN ALLEY CROPPING SYSTEM. Nitrogen (N) is the most important nutrient for crop growth and production. This study was conducted to determine whether in each of six seasons and after these seasons the N-soil, N-green manure, N-green manure + urea, and N-urea is still available for crops. Upland rice and corn were planted successively for six seasons. In each season upland rice and corn were planted and applied with N-fertilizers at rate of: control (0N), N1 (100% green manure), N2 (50% green manure + 50% urea), N3 (100% urea). N-15 labelled urea was added at each season to determine the A-value of the crops. In each seasons it was shown that crops used N-soil as well as N-fertilizer. With the increase of the availability of N-fertilizers the use of N-soil decrease and so could preserve N-soil. With preservation of N-soil it could be assumed that soil quality has increased. The N-15 method could be used to determine the availability at each fertilizer rate?s in each season and at the end of the sixth season

Teknik Nuklir untuk Penelitian Hubungan Tanah Tanaman : Perhitungan dan Interpretasi Data

iii.130 hal.;21 c

THE RESPONSE TO P-DERIVED FROM PHOSPHATE ROCK AND TSP BY CROPS GROWN IN A SIMULATED CROP ROTATION SYSTEM

ABSTRACT THE RESPONSE TO P-DERIVED FROM PHOSPHATE ROCK AND TSP BY CROPS GROWN IN A SIMULATED CROP ROTATION SYSTEM. A green house experiment was carried out on a simulated crop rotation system of upland rice-soybeanmungbean to determine the effect of P-derived from different phosphate rock (PR) sources and TSP using 32 P. The data obtained reveal that all the P-sources has a significant effect on the growth of all the three crops, expressed in dry weight, % P-total and total P-uptake (mg P pot -1 ). For the P-source it was shown that % P-derived from PR/TSP and their uptake (mg P pot -1 ) was quite high, showing that the PR s applied were of good reactivity. The residue of the PR s has also still a good effect on plant growth than that of TSP. The efficiency of PR s was far below that of TSP. This apparently was due to the high rate of application, ten times the rate of TSP