Nutrient Loss by Erosion under Different Land Use System in Babon Catchment,, Central Java, Indonesia

Transcription

1 Nutrient Loss by Erosion under Different Land Use System in Babon Catchment,, Central Java, Indonesia Kasdi Subagyono 1, T. Vadari 2, and Sukristiyonubowo 2 1 West Java Assessment Institute for Agricultural Technology 2 Indonesian Soil Research Institute International Workshop for AUF s networks Integrated Water and Soil Management: Resources, Infrastructures and Risks in rural and urban areas Hanoi, 4-9 November 2007

2 Introduction Erosion is widely considered as the major cause of soil degradation Loss of nutrients is the one of significant cause of degradation prior to erosion However, most of the study on erosion has been directed on the process of losing soil material and sedimentation with less concern on nutrient loss

3 Objective To understand the impact of dynamic of land use system and land management systems on erosion and nutrients losses

4 Site Description Java Island Location: Babon Sub catchment, Central Java Total area 285 ha Tegalan : 1.1 ha Rambutan : 0.9 ha Kalisidi : 13 ha

5 Characteristic of catchments used in the study Catchments Tegalan Rambutan Kalisidi Babon Area (ha) Runoff coef. (%) 1) Soils Andic Eutropepts Andic Dystropepts Andic Dystropepts Typic Tropaquepts 1) Based on March 2000 to February 2001 measurement Land use/farming system Cassava, maize, some trees in 2000 and 2001 and fodder grass covering about 60% area starting in December % Rambutan, 5% Shrub 100% Rambutan, lower catchment encroached for annual crops All above + Rice field of about 17 ha Dominant slope (%) 45 47(46) 22 55(40) 22 55(37) 0 55(30) Rainfall: 3820 mm/year Fertilizers : Urea, TSP, KCl

6 Methods (1) The study was conducted from 2001 to 2004 Land Use Treatments : Paddy rice field (PRF) with paddy rice crop based system Tegalan (TGL) with annual food crops based system Rambutan (RBT) with Rambutan crop based system Kalisidi (KLD) with Rambutan and shrub based system

7 Methods (2) Land Management Treatments Farmers treated different land management practices in each land use system: Tillage and fertilization in PRF Encroachment by tillage for cassava in RBT Little encroachment by tillage in KLD

8 Methods (3) To assess nutrients balance under the different land used systems (TGL, RBT, KLD, and PRF), nutrients gain and loss were monitored and referred to as input and output data respectively The study has only be directed to assess the dynamic of NPK Simple treatments of farmer practices and improved technology were set up

9 Basic approach for assessing nutrient balances in terraced paddy field NH3; N20 Rainfall Terraced paddy field Fertilizers Organic Irrigation Rice grains and straw 40 cm Weathering Plow pan layer Soil solution Biological processes Runoff/ Erosion Leaching

10 Data collected and methods for the INPUTS unit in the assessment of N, P, and K balances at terraced paddy field system Input data Code and Nutrients Data required/collected Method of quantification Mineral Fertilizers IN-1: N, P, and K Type of fertilizer applied Amount of fertilizer Applied Nutrient content in fertilizer Field measurement Field measurement Laboratory analysis Organic Fertilizer IN-2: N, P, and K Amount of rice straw remain in the field Field measurement Amount of rice straw recycled Field measurement Nutrient content in rice straw that remain in the field Laboratory analysis Nutrient content in recycled rice straw Laboratory analysis Irrigation IN-3: N, P, and K Water level Discharge Nutrient concentration in water Field measurement Field measurement Laboratory analysis Rainfall IN-4: N, P, and K Daily, monthly and annual rainfall Nutrient content in rainfall N, P, and K deposition in rainfall Field measurement / record Laboratory analysis Study literature (for checking ) B N F IN-5: N Only Secondary data/study literature

11 Data collected and method for OUTPUT unit in the assessment of N, P, and K balances at terraced paddy field system Output data Harvested Product Crop residues Code and Nutrients OUT-1: N, P, and K OUT-2: N, P, and K Data required/collected Rice grain yield Nutrient content in rice grain Rice straw production Amount of recycled rice straw Method of quantification Field measurement Laboratory analysis Field measurement Field measurement Amount of rice straw for feeding Field measurement Nutrient content in rice straw Laboratory analysis Erosion OUT-3: N, P, and K Water level Discharge of outlet Nutrient concentration in suspended sediment Field measurement Field measurement Laboratory analysis Sediment concentration Soil and nutrient losses Laboratory analysis Estimation based on field measurement : Soil loss = q x sediment concentration Nutrient loss = soil loss x nutrient concentration in sediment Leaching OUT-5: N and K Secondary data/ Study literature. It may be neglected since there is pan layer that water can not pass through

12 Methods (4) Assumptions and Limitations The calculated value was based merely on actual measurement of inputs and outputs covered in the system Total nitrogen, phosphorus, and potassium were the only nutrients considered If there was no disturbed soil structure by tillage, concentration incoming and outgoing sediments was considerably equal The calculation of soil and nutrient gain and losses were mainly based on the important activities conducted by the farmers

13 Methods (7) Quantifying Nutrient Loss (1) Sediment Concentration = (Ceisiolka and Rose, 1998) Oven dry mass sediment Vol. of (sediment + water) (2) Suspended Load = Discharge x Sediment Concentration (Hashim et al., 1998 and Tarigan and Sinukaban, 1989) (3) Nutrient loss = Soil loss x Concent. of nutrient in sediment (Brata, 1999; Hashim et al., 1998)

14 Methods (8) Nutrients loss evaluation? Nutrient loss was evaluated based on the actual measurement of N, P and K loss through erosion and crops harvest

15 Soil Loss through Erosion under Different Land Use Systems

16 Soil loss through erosion under different land use in dry land areas of Babon catchment Sediment Yield (t/ha) T-2001 T-2002 T-2003 T-2004 R-2001 R-2002 R-2003 R-2004 K-2001 Susp load Bed load T : Tegalan R : Rambutan K : Kalisidi K-2002 K-2003 K-2004 Soil loss under seasonal based cropping system (TGL) was higher compared with that under trees based cropping system (RBT and KLD)

17 Impact of Encroachment? Significant increase has been obviously observed under Rambutan and Kalisidi systems There was land encroachment done by farmers to be used for cassava and the seasonal crops Encroachment significantly increased soil loss

18 Water yields under different land use system Water yield (mm/min) Rainfall Tegalan Rambutan Kalisidi :48 11:19 11:26 11:33 11:40 11:46 11:53 12:00 12:07 12:14 12:21 12:28 Time Rainfall amount (mm) January 29, 2004 storm event Storm charactersitics Storm period (min) a Rainfall (mm) Maximum rainfall intensity (mm/min) Total watr yields (mm/min) b Tegalan Rambutan Kalisidi Values ,2 5,8 0,04 0,01 0,24 a,b Calculation was done using January 29, 2004 storm of hrs to hrs period data by excluding base flow

19 Nutrients Loss through Erosion under Different Land Use Systems

20 N, P and K losses by erosion under different land management system in dry land areas N, P and K (Kg/ha/year) TGL Loss of N, P 0.15 and K were higher than 0.12 that in RBT system and mix of 0.09 rambutan and shrub 0.06 The higher loss of N, P 0.03 and K in TGL was due to 0 high rate of erosion N P K RBT KLD TGL Wet season 2003/2004 N, P, and K (Kg/ha/year) RBT, KLD

21 The balance of N, P and K in the terraced rice field Components Inputs Fertilizer Irrigation Straw Total Outputs Loss through harvest: -Grain -Straw Loss through erosion: -Suspended load -Bed load Total Balance FP N IT FP P (kg/ha/year) IT FP K IT FP: Farmer Practices; IT: Introduced Technology

22 N, P and K balance under farmer practices and introduced technology in the rice field N, P and K (kg/ha/year) N in N out N Balance P in P out P Balance K in K out K Balance N and K are mobile and easy to loss prior to leaching during drainage period -150 FP IT

23 N, P and K loss and on site cost of soil erosion Land use Nutrient loss and Equaled fertilizers (kg/ha/year) N Urea 1) P SP-36 2) K KCl 3) 2 O 5 2 O Cost 4) (US$/ha /year) Tegalan Rambutan Kalisidi Rice field * ) Urea contains 46% of N 2) SP-36 contains 36% of P2O5 3) KCl contains 60% of K2O 4) Price of Urea, SP-36 and KCl fertilizers were respectively 1,500; 2,200 and 3,000 rupiahs per kg (1 US$ = 9,090 rupiahs as of May 2, 2007 curse) *Land management under farmer practices

24 Management to reduce nutrients loss

25 Management to reduce nutrients loss? Erosion control Nutrient enrichment 66% of rice straw was left in the field 33% for fodder Fertilizers application Treatments Nutrients balance N P K Rice straw for fodder (kg/ha/year) Farmers practices -Introduced technology Application of 66% of rice straw - Farmers practices - Introduced technology

26 Significance of Grass Planting for Conservation Measure Soil lost can be control by implementing soil conservation measure using grass (Benggala grass/panicum maximum) planting either in the strip system or it is planted in the lip of the terrace. After a year grass planting, the soil lost can be reduced as much as 50% in the first year and almost 90% after the second year (2003)

27 Integrated grass plating and cattle fattening for sustainable erosion control Manure Farmers Since the introducing cattle provided an additional income for farmer through fattening program, grass planting was initially accepted

28 Conclusions NPK loss in the area under rice base cropping system with intensive land management system is the highest among the land use systems treated In dry land areas, NPK loss under seasonal based cropping system is higher than that under trees based cropping system By considering equaled fertilizers based on the nutrient losses, for the PRF cultivation, farmers paid more than US$ 16 per ha annually. Under TGL system, the cost to be paid more than US$ 4 per ha annually, but it was less than US$1 per ha annually if their land was cultivated for tree crops as it was done for RBT and KLD

29 Recommendations To reduce on-site cost of erosion and nutrients loss: Conservation measures and appropriate land management techniques have to be implemented in combined with efficient use of fertilizers Minimum tillage in rice field can be applied to minimize disturbance and to reduce soil loss through erosion

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