Sediment and Nutrient Mobility in Terraced Paddy Fields Under Traditional Irrigation System

Sediment and nutrient mobility in terraced paddy fields under traditional irrigation system have been investigated in Keji Village, the Semarang District during the Wet Season 2003-2004. The aims were to evaluate the incoming and outgoing sediment and nutrient during rice growth cycle and to study the mobility of sediment and nutrient in the wet season. The treatments included Farmer Practices, Farmer Practices + Rice Straw, Improved Technology, and Improved Technology + Rice Straw. The discharge of irrigation water during puddling was the greatest varying between 2.55 ± 1.23 and 3.10 ± 0.55 l second-1, while during the vegetative phase was the lowest ranging from 0.33 ± 0.15 to 0.54 ± 0.15 l second-1. At the generative stage was about 1.38 ± 0.28 to 1.60 ± 0.06 l second-1. Furthermore, the discharge of suspended sediment during puddling varied between 0.89 ± 0.20 and 1.31 ± 0.34 l second-1, while atvegetative phase was the lowest ranging from 0.21 ± 0.07 to 0.78 ± 0.52 l second-1. At generative stage was about 1.13 ± 0.06 to 1.32 ± 0.09 l second-1. Only during the puddling that the incoming sediment was lower than outgoing sediment. The total amount of deposited sediment varied between 647 and 1,589 kg ha-1 season-1 from the total incoming sediment of 2,715 to 5,521 kg ha-1 season-1. In contrast, the incoming dissolved nutrient (nitrogen, phosphorus and potassium) was trapped in the paddy field areas, varying between 7.20 and 13.62 kg N; 0.13 and0.20 kg P; and from 7.25 to 13.42 kg K ha-1 season-1. There were no significantly different among treatments, both for sediment and nutrient deposited. These results demonstrate that terraced paddy field system is not only place for producing rice, but also providing an environmental services, like nutrient and sediment conserving

Sediment Trapping By Terraced Paddy Field On Slopping Agricultural Land

Terraced paddy field is not only important for rural food security, but also for trapping sediment in the slopping land. The aims of this research were to quantify the amount of incoming and outgoing sediments and to study sediment movement behavior during harrowing and fertilizing under traditional irrigation of terraced paddy field system. This study was carried out at Keji Village, Semarang District, Central Java during two cropping seasons, a wet season 2003/04 and a dry season 2004. A paddy field with eight terraces was selected. The terraces were flat, different in size and descending to the river. Sediment samples were taken at harrowing and fertilizing activities. The results indicated that at harrowing, outgoing sediment was higher than incoming both during the wet and the dry seasons. About 0.53 and 0.27 t ha-1 day-1 of soil were eroded during harrowing in the wet and the dry seasons, respectively. However, a week before and after fertilizing, both in the wet and the dry seasons, the amounts of incoming sediment were higher than the outgoing one. In the wet season, the amounts of incoming sediments were three to four times higher than the outgoing one, both a week before and after fertilizing. During the wet season, about 0.31 and 0.34 t ha-1 day-1 of sediment was yielded a week before and after fertilizing, respectively. During the dry season, the incoming sediments were ten times higher than the outgoing one. On an average the sediment yields were about 0.07 and 0.08 t ha-1 day-1 a week before and after fertilizing, respectively. Terraces having greater areas deposited more sediment than those with smaller sizes. During a week before and after first fertilizing, the total amounts of incoming sediments were 6.44 and 1.19 t ha-1 for the wet and dry seasons, while that of outgoing sediments were 1.89 and 0.14 t ha-1 for the wet and dry seasons, respectively. This indicates that terraced paddy fields are not only producing rice, but also providing environmental service in term of sediment trapping. This external service minimizes sedimentation in the downstream

Nutrient balances in terraced paddy fields under traditional irrigation in Indonesia

In Indonesia, rice is not only staple food, but also a source of income, providing job for the villagers. In the past, most studies focused on lowland rice using half or fully regulated technical irrigation systems to increase rice production and improve farmers’ income. Land conversion to non agricultural purposes, competitions in water demands with other industries, and socioeconomic and biophysical problems resulted in shrinking total surface area available for cultivating rice. Hence, intensifying terraced paddy fields became very important. The current study, therefore, focuses on these. The mobility of sediments and nutrients, nutrient uptake during rice growth and the effect of rice straw addition on rice production were evaluated. Sediment was found to be mainly displaced during harrowing in the terraced paddy fields under traditional irrigation, both in the wet and dry seasons. In contrast, sediments were deposited on every terrace a week before and after fertilising. Both at harrowing and during fertilising, the amounts of incoming dissolved nutrients were higher than outgoing. It may be concluded that terraced paddy field systems are not only the way to produce rice, but also provide environmental services. It is strongly recommended to protect these areas to reduce erosion and other downstream negative effects. Application of 100 kg ha-1 season-1 of urea, TSP and KCl along with 33 % of the rice straw produced in the previous growing season always results in the highest N, P, and K concentrations in shoot and roots, nutrient uptakes and significantly increased rice yields, both in the wet and dry seasons. However, application rates of 100 kg ha-1 season-1 of urea, TSP and KCl along with 33 % of the rice straw produced in the previous growing season presents positive P balances, but negative N and K balances. This illustrates that urea and KCl application rates are not sufficient to replace N and K removed by grains and straw. Towards sustainable rice farming in terraced paddy field systems, application rates of 200-250 kg of urea, 100 kg of TSP and 200 kg of KCl ha-1 season-1 along with recycling rice straw for at least 33 % of its production are highly recommended. Scaling up this study from farm to district level shows that when a minimal rice yield of 5 t ha-1 is expected and 33 % of the rice straw production is recycled, the current recommended fertiliser rates remain economically and environmentally valid. However, at an expected rice yield of 5 t ha-1 and when no rice straw is recycled, application rates of 280 kg of urea, 100 kg of TSP and 300 kg of KCl ha-1 season-1 are needed. Conventional farmer practices with a urea application of 50 kg ha-1 season-1 always show the lowest nutrient concentration in the rice, the lowest rice yield and negative nutrient balances. Hence, these practices may not longer be recommended. Realising that intensification of livestock production also needs rice straw, the use of 67 % of the rice straw production as cattle feed and returning 33 % to the field may be a realistic recommendation

Temporal and Seasonal Variation of Sediment Movement in the Terraced Paddy Fields System

Temporal and seasonal variation of sediment movement in terraced paddy fields has been studied at Keji Village, in Semarang District for the Wet Season 2003-04 and the Dry Season 2004. Twelve terraced paddy fields with different number and size of terraces were used in this research,corresponding to four treatments and three replications. Terraces were flat, different in size, and descending to the river. The objective was to study the temporal and seasonal variations of sediment movement during rice growth in the wet season and the dry season. Measurements were conducted in the four treatments being tested including Farmer Practices, Farmer Practices + Rice Straw, Improved Technology, and Improved Technology + Rice Straw. Sampling and measuring of irrigation water discharge and suspended sediment were carried out at puddling, before planting, vegetative stage, and at generative stage. The highest temporal discharge as well as sediment concentration of irrigation water and suspended sediment both in wet and dry seasons were observed at the puddling stage and significantly different with the following rice growth stages. In contrast, the lowest temporal discharge and sediment concentration were found at the vegetative stage. Seasonal discharge and sediment concentration of irrigation water and suspended sediment in wet season were higher than in dry season. The highest incoming and outgoing sediments both in wet and dry season were observed at the vegetative stage and significantly different at generative stage, planting and puddling. The amount of seasonal incoming sediment were 4,422 ± 361 and 1,779 ± 126 kg ha-1 and the outgoing sediment were 3,345 ± 258 and 1,400 ± 113 kg ha-1 for the wet season 2003-04 and dry season 2004, respectively. The surplus of incoming sediment by outgoing sediment demonstrates the environmental services provided by terraced paddy fields system

Plot Scale Phosphorous and Potassium Balances of Newly Opened Wetland Rice Farming Originated From Wetland

Development of newly opened wetland rice fields both from dry land and wetland in Indonesia are important to meetrice growing demand, increase soil productivity, keep rural food security and provide jobs as well as generateincome. Most soils of newly opened rice fields are low in P and K contents, but the farmers do not apply P and Krecommended fertilisers. The study was conducted on newly opened wetland rice farming in Panca Agung village,Bulungan District, East Kalimantan Province, Indonesia in 2009. The aims were to evaluate phosphorous andpotassium input – out of newly opened wetland rice and to validate the P and K recommendation. Six treatmentswere tested including farmers practices (as control), farmer practices + straw compost + dolomite, NPK withrecommendation rate in which N and K was split in two applications, NPK with recommendation rate in which N andK was split three applications, NPK with recommendation rate + straw compost + Dolomite , in which N and K wassplit three applications, and NPK with recommendation rate + straw compost + dolomite, in which N and K weresplit two applications. The N, P and K rates were 250 kg urea, 100 kg SP-36 and 100 kg KCl ha-1 season-1, while thefarmer practices 100 kg urea and 100 kg SP-36 ha-1 season-1. Parameters to be measured were concentration P andK in mineral fertilizer, compost, irrigation water and grains as well as straw. The results showed that surplus Pranged from 5.75 to 12.85 kg P ha-1 season-1, meaning that SP-36 application rate was more than enough to replace Premoved by harvest product. In contrast, potassium application rate should be increased from 100 to 200 kg KClha-1 season-1 to fix K removed by harvest product. However, when the compost will also be increased to 3 Mg ha-1season-1 K fertilizer can be increased to 150 kg KCl ha-1 season-1 to substitute K taken away by rice harvest productand to keep higher rice grain yield. These P and K recommendation rate imply that total SP-36 and KCl should beavailable at district level will be about 984.9 Mg SP-36 and 1.477 Mg KCl district -1 season -1, respectively.Keywords: Newly opened wetland rice; nutrient balance; nutrient input; nutrient losses; plot scale wetland[How to Cite: Sukristiyonubowo, K Nugroho and S Ritung. 2012. Plot Scale Phosphorous and Potassium Balances of Newly Opened Wetland Rice Farming Originated from Wetland. J Trop Soils 17 (3): 227-237. doi: 10.5400/jts.2012.17.3.227][Permalink/DOI: www.dx.doi.org/10.5400/jts.2012.17.3.227]&nbsp

Rice Yield and Nutrient Removal Through Harvest in Newly Developed Lowland Rice Field in Bulungan District, North Kalimantan

. Nutrient removal through rice harvest of Ciherang variety planted in newly developed lowland rice field was studied in Bulungan District, in 2013. The aims of this research were to evaluate the amount of nutrients taken out by rice harvest and to properly manage its fertility to sustain high rice yield. Five treatments were tested, T0: Farmers practices, T1: Package A (NPK at recommendation r ate + Dolomite), T2: Package B (NPK at recommendation rate + dolomite + Compost + Smart), T3: Package C (¾ NPK at recommendation rate + Compost + Dolomite + Smart), and T4: Package D (NPK at recom-mendation rate + Compost + Dolomite + Smart). They were arranged in a Randomized Complete Block Design and replicated three times. The results showed that the highest rice biomass yield (rice grains, rice straw and rice residues) was from the package D, whereas, the highest concentrations of N, P, and K were found in rice grain of Package B. The highest nitrogen and phosphorous removals were from rice grains and for potassium was from rice straw. Depending on the treatments, total nutrient removal through rice grains and rice straw varied: from 30.96 ± 2.93 to 67.82 ± 8.93 kg of N; 12.83 ± 2.15 to 27.53 ± 14.11 kg of P; and 55.10 ± 2.92 to 101.84 ± 6.02 kg of K ha-1 season-1. To avoid nutrient mining and to maintain the soil fertility, about 67 to 150 kg urea, 65 to 140 kg SP-36 and 105 to 196 kg KCl ha-1 season-1 should be applied to the soil

Farm Scale Nitrogen Balances for Terraced Paddy Field Systems

Nitrogen balance at farm scale is not only important to refine the site specific nitrogen fertiliser application rate, but also to estimate how much nitrogen fertiliser should be provided every planting season at district level. The nitrogen fertiliser stock for the district can be calculated by multiplying the total planting areas with nitrogen fertiliser rate per hectare. The aims were to evaluate the nitrogen balance of terraced paddy field systems under conventional farmer practices and improved technologies during the wet season 2003-04 and dry season 2004 and to predict how much nitrogen fertiliser should be provided in every planting season for wetland cultivation in the Semarang district. The nitrogen input-output assessments were carried out in terraced paddy fields for the conventional farmer practices (CFP), conventional farmer practices + rice straw (CFP+RS), improved technology (IT), and improved technology + rice straw (IT+RS) treatments. Balances were computed based on the differences between input and output. Nitrogen originating from fertiliser (IN-1), recycled rice straw (IN-2), irrigation (IN-3), and precipitation (IN-4) were grouped as input. Nitrogen removal by rice grains (OUT-1) and rice straw (OUT-2) was considered as output. The input-output analyses showed negative nitrogen balances for all the treatments, both in the wet season 2003-04 and the dry season 2004. The more nitrogen deficit was observed when the nitrogen volatilisation was considered. The nutrient inputs, particularly coming from inorganic fertilisers, were not sufficient to replace the nitrogen removed by rice grains and straw. The application of only 50 kg of urea/ha/season with and without returning rice straw was not enough to reach the optimal yield and should be left out. To balance the nitrogen deficit and to improve cultural practices in wetland rice farming especially terraced paddy field system, about 200 -250 kg urea/ha/season is recommended when the ammonia volatilisation is not considered, where as when the ammonia volatilisation is taken into account about 250-300 kg urea/ha should be added. When the rice yield of 5.73 t/ha is targeted as reached in the IT+RS treatment even higher and the planting areas in the Semarang district is about 24.833 ha for the wet season, the amount of urea should be provided will be about 4.97-6.21 million tons/season/district, meanwhile for the dry season when about 18,440 ha wetland rice is expected to be cultivated is about 4.61 to 5.53 million tons urea/season/district should be available