Influence of SP-36 and Phosphate Rock on Changes in Soil Available P, Leaf P Content, and Growth of Physic Nut (Jatropha curcas L.) in an Ultisol

A study was carried out to determine the effects of rates and types of P fertilizer (SP-36 and Phosphate Rock) on the growth of physic nut (Jatropha curcas L.), leaf P content, and soil available P in an Ultisol in a glasshouse. The treatments consisted of four rates of P (0, 50, 100 and 150 mg P2O5 kg-1 soil) given in two different types of P fertilizer, namely SP-36 (total P2O5 = 36%) and Phosphate Rock (total P2O5 = 28%, particle size distribution = 75%<0.25 mm, 85%<0.50 mm, 90%<1.00 mm). Treatments were arranged in a Completely Randomized Design with three replications. The results showed that at the rates of 50 and 100 kg P2O5 ha-1, there was no difference in soil available P due to the application of SP-36 and Phosphate Rock, indicating that both types of P fertilizer had the same dissolution values after 8 months of P fertilizer application. At the rate of 50 kg P2O5 ha-1, the application of SP-36 and Phosphate Rock gave the same leaf P content. This could indicate that up to the first 8 months, the addition of the cheaper Phosphate Rock and the SP-36 to the soil had similar effectiveness. The response of tree biomass to P fertilization followed a quadratic pattern, in which for the application of Phosphate Rock, the P optimum rate was achieved at the rate which was lower than that for the application of SP-36. This suggests that the application of Phosphate Rock to physic nut trees was more efficient and effective compared to the application of SP-36.Keywords: Leaf P, phosphate Rock, physic nut (Jatropha curcas L.), soil available P, [How to Cite: Achmad AR. 2014. Influence of SP-36 and Phosphate Rock on Changes in Soil Available P, Leaf P Content, and Growth of Physic Nut (Jatropha curcas L.) in an Ultisol. J Trop Soils 19: 9-15. Doi: 10.5400/jts.2014.19.1.9] 

Changes in Soil Available Phosphorus, Leaf Phosphorus Content and Yield of Sword Bean (Canavalia ensiformis (L.) DC.) by Application of SP-36 and Phosphate Rock on Acid Upland Soil of East Lampung

A glasshouse trial was performed to determine changes in phosphorus (P) nutrition and the yield of sword bean (Canavalia ensiformis (L.) DC.) following the application of different rates and types of P fertilizer in an acid upland soil of East Lampung. Two different types of P fertilizer, namely SP-36 (total P = 36%) and Phosphate Rock (PR) (total P = 24.3%, particle size distribution = 75% <0.25 mm, 85% < 0.50 mm, 90% < 1.00 mm) were used in the trial. For the treatment, each P fertilizer type consisted of four rates (0, 50, 100 and 150 mg P2O5 kg-1 soil) that were arranged in a Completely Randomized Design with four replications. The results showed that the application of P fertilizers had significant effects on soil pH, soil plant-available P, the potential-P (HCl 25%), leaf N and P concentrations, the yield of sword bean. Increased rates of both forms of P fertilizer increased the soil pH values. As the soil used had low pH and very high exchangeable Al, hence, this result is most probably related to the addition of Ca2+ to the soil solution that resulted from the P fertiliser applied (liming effect), either from SP-36 (monocalcium phosphate) or PR (flour apatite). There was no difference in soil available P concentration due to the different in P fertilizer types, indicating that 4 months after the fertilizer application, the relatively insoluble Phosphate Rock had the same P solubility with SP-36. Increased rates of both forms of P fertilizer increased the sword bean yield. For the application of 0 kg P2O5 ha-1, although sword bean crops had pods, but, they did not give any seed. Whereas, at the addition of P fertilizer at the rate of 50, 100, and 150 kg P2O5 ha-1 for both P fertilizer types, the crops were able to give the seeds in the pods. [How to Cite: Achmad AR. 2015. Changes in Soil Available Phosphorus, Leaf Phosphorus Content and Yield of Sword Bean (Canavalia ensiformis (L.) DC.) by Application of SP-36 and Phosphate Rock on Acid Upland Soil of East Lampung. J Trop Soils 19: 29-36. Doi: 10.5400/jts.2015.20.1.29][Permalink/DOI: www.dx.doi.org/10.5400/jts.2015.20.1.29

PENENTUAN KEBUTUHAN NITROGEN TANAMAN JAGUNG (Zea mays L.) PADA BERBAGAI JARAK TANAM DALAM TUMPANGSARI DENGAN KACANG TANAH (Arachis hypogeae L.) DI LAHAN KERING MALUKU TENGAH

Most people in Maluku Islands have long used non-rice food consumption, especially tuber crops and maize. The development of diversification of non-rice food consumption certainly needs to be supported by the availability of adaptive crop cultivation technology to climate change. Cropping pattern is one of the appropriate steps for smallholder farmer to increase land productivity. An experiment of maize/peanut intercropping pattern had been conducted to determine optimum Nitrogen (N) rate for maize at different planting spacings in intercropping pattern with peanut in dryland of Makariki Village, Central Maluku. The experiments were arranged in a Split Plot Design with 3 (three) replicates. The main plot was maize spacing, namely: (i) J1 = 80 x 25 cm, 6 rows of maize, 2 rows of peanut, (ii) J2 = 160 x 25 cm, 3 rows of maize, 4 rows of peanut, and (iii) J3 = 240 x 25 cm, 2 rows of maize, 6 rows of peanut. The sub-plot was N rate (kg/ha), namely: (i) N0 = 0-0-0, (ii) N1 = 45-50-60, (iii) N2 = 90-50-60, (iv) N3 = 135-50-60, and (v) N4 = 180-50-60. The results showed that plant height, cob circle and yield of maize grown at different planting spacings in intercropping patterns in Makariki, Central Maluku affected by N fertilizer application. The application of N fertilizer increased growth and yield of maize by following a quadratic pattern. The use of maize spacing of J1 (80 x 25 cm) in intercropping with peanut requires the addition of the optimum N rate of 302 kg urea/ha, which gave the highest maize yield (t/ha) compared with other planting spacings

Analysis of Climate Change Impacts on Agricultural Water Availability in Cimanuk Watershed, Indonesia

Climate change has been affecting agricultural water resources dynamics spatially and temporally. This article presents analysis results of climate change impact on agricultural water availability in Cimanuk Watershed, Indonesia. STREAM was utilized to model agricultural water availability through FAO MOSAICC web application. Climate spatial data time-series were generated using 3 Global Climate Model (GCM), i.e.,: CanESM2, CNRM-CM5, and MPI-ESM-MR following two climate change scenarios of RCP4.5 and 8.5. Model inputs were split into three periods of 1981&ndash;2010 (historical), 2010&ndash;2039 (near-future), and 2040&ndash;2069 (far-future). Historical data model validation showed the efficiency coefficient of the observed and simulated discharge data ratio was 0.68. The results showed a decreasing volumetric water availability from all generated climate data and scenarios, identified by comparing the discharge normal distribution of the historical and future data periods. Whereas, trend analysis of RCP4.5 scenario showed increasing maximum discharge of Cimanuk river using CanESM2 and MPI-ESM-MR GCM&rsquo;s data, with a Mann&ndash;Kendall coefficient of 3.23 and 3.57. These results indicate a different agricultural water balance status within the watershed area, particularly a &ldquo;very critical&rdquo; water balance in Indramayu and Majalengka, &ldquo;critical&rdquo; in Garut, and &ldquo;close to critical&rdquo; in Sumedang Regency