MOVEMENT OF CHLORIDE INTO A WELL-DRAINED SOIL

Chemical leaching from soil surface will cause groundwater pollution. Researches showed spatial correlation of the leaching chemicals. Based on the fact, a filed research was conducted at Maury silt loam soil (fine, mesic, mixed, Typic Paleudalf) to evaluate spatial variations of anion movement, in tis case was Cl, into and below rooting zone. Source of chloride, SrCl2.6H2O, was evenly distributed on soil surface within a 18 x 18 m2 plot in University of Kentucky Experimental Station, Lexington, Kentucky USA. Soil was sampled for 4 times (after receiving 166, 310, 586, 1085 mm rainfall), in every 10 cm depth for 54 points within the plot. The result showed that Cl- movement did not show spatial model from soil surface into 100 cm profile in every sampling date. Therefore, based on analysis of variance, Cl- concentration was significantly different from one depth to another within one sampling time. Cl- concentration found on the depth of 100 cm was 75, 58, 27, and 15% for sampling time I, II, III, and IV, consecutively. Key Words: groundwater pollution, anion leaching, agricultural chemicals, spatial structur

STRONTIUM MOVEMENT INTO PROFILE OF MAURY SILT LOAM SOIL

Groundwater pollution due to chemcal application in agriculture activities has caused much public concerns. Based on the researches having been conducted, it was resulted that chemical leaching in soil frequently showed spatial pattern. Based on the fact, a field research was conducted in Maury silt loam soil (fine, mesic, mixed, Typic Paleudalf) to evaluate spatial variety of Sr movement into and below rooting zone. Chemical material SrCl2.6H2O was evenly distributed on soil surfacein a 18 x18 m plot. Soil samples were taken 4 times (after receiving rainfall 166, 3, 586, and 1085 mm) in 54 locations within the plot. At each sampling undisturbed soil was taken from surface until 100 cm depth, then the Sr element was analyzed from each 10 cm depth. The results showed that there was no spatial pattern found for Sr movement within a 100-cm soil depth in each sampling date. Therefore, based on the analysis of variance, it was about 95% of Sr2+ found on 0-20 cm soil depth even though after receiving 1085 mm rainfall. Key Words: groundwater pollution, agricultural chemicals, spatial structur

PHYSICAL CHARACTERISTICS OF ULTISOLS AND THE IMPACT ON SOIL LOSS DURING SOYBEAN (Glycine max Merr) CULTIVATION IN A WET TROPICAL AREA

Physical characteristics are among soil properties affecting the susceptibility to erosion. Determination of physical characteristics of Ultisol was aimed to evaluate the dynamics of the soil properties as well as the impact on soil erosion and runoff (RO) during soybean cultivation in a wet tropical area. Soybean was planted within erosion plots (18 m2) at 25% slope in Ultisols Limau Manis (having > 5000 mm annual rainfall).Soil samples for physical properties (soil texture, bulk density, total pore, permeability, aggregate stability,and organic carbon) as well as amount of RO and soil loss were analyzed at 5 different times (stages) during the cultivation. The results showed that there were fluctuations in physical properties of Ultisol during the cultivation. Likewise, the amount of runoff and soil loss also changed during the study. Among the physical properties analyzed, the aggregate stability index of the soil was highly correlated to the amount of RO (R2=0.73) and soil loss (R2=0.94). The amount of RO and soil loss was controlled by soybean development at the average rainfall intensity (≤ 36 mm/day), not at rainfall intensity (>36 mm/day). Thus, It is suggested not to open heavy clayey and low organic carbon (OC) soils for seasonal crop farming during rainy season in wet tropical areas

Chemical Characteristics of Soils Based on Toposequence under Wet Tropical Area in Bukit Sarasah Padang

Topography is a factor affecting soil characteristics. Chemical characteristic of a soil is a factor determining the productivity of the land. A research was conducted in Bukit Sarasah Padang, an area receiving > 5000 mm rainfall annually. The purpose of this research was to determine the chemical characteristics of soils at sequence topography in hill-slope of Bukit Sarasah. Soils were sampled at 3 different altitudes in the research area from 315 m – 515 m asl with 100 m interval. At each location, soil samples were taken from two depths (0-20 cm and 30-50 cm) for soil chemical characteristics (pH, CEC, organic-C, N-total, C/N, Ca-, Mg-, K-, Na-, Al-, and H-exchangeable). Based on the data resulted, it was found that there was a tendency of decreasing soil organic matter (SOC) content by increasing location from 315 to 515 m asl as well as from the top 0-20 cm to 30-50 cm soil depth. The same tendency was also found for the CEC, pH, N-total, and C/N ratio of the soil. On the other hand, exchangeable-Al and -H tended to increase by increasing elevation in Bukit Sarasah. There was no significant difference found for the concentration of exchageable cations among the elevations and between the depths. The soil chemical characteristics on the top 20 cm were generally better than those on 30-50 cm soil depth, however, different elevation did not gave significant difference of the concentration

Organic carbon sequestration under selected land use in Padang city, West Sumatra, Indonesia

Organic carbon is a potential element to build biomass as well as emitting CO2 to the atmosphere and promotes global warming. This research was aimed to calculate the sequestered Carbon (C) within a 1-m soil depth under selected land use from 6 different sites in Padang city, Indonesia. Disturbed and undisturbed soil samples were taken from several horizons until 100 cm depth at each location. Soil parameters observed were organic carbon (OC), bulk density (BD), and soil texture. The result showed that soil OC content tended to decrease by the depth at all land use types, except under rice field in Kurao-Nanggalo which extremely increased at >65 cm soil depth with the highest carbon stock. The soil organic carbon sequestration from the highest to the lowest according to land use and the location is in the following order mix garden- Kayu Aro > mix garden- Aie Pacah > Rangeland- Parak Laweh >seasonal farming- Teluk Sirih > rice field- Kampuang Jua

Role of Gliricidia sepium in Improving Aggregate Stability of Ultisol Limau Manis Padang: A LABoratory study

There is no much public concern about soil aggregate stability improvement of a soil.  This is due to the fact that it does not directly affect crop yield for a short term, but it determines sustainable agriculture and development for a long term.  This research was aimed to investigate soil physical properties especially soil aggregate stability of Ultisols after fresh OM application, then to determine the exact OM dosage to improve the stability.  Ultisols used was from Limau Manis (± 367 m asl), an area in lower footslope of Mount Gadut, having wet tropical rainforest. Due to land use change, farming activities in that sloping area could enhance erosion process in the environment.  Therefore, efforts to anticipate the erosion must be found.  Fresh OM applied was Gliricidia sepium which was found plenty in the area.  Five levels of fresh Gliricidia sepium, were 0, 5, 10, 15, and 20 t/ha.  Top soil (0-20 cm depth) was mixed with OM, then incubated for 3 months in glasshouse.  The results after a 3-month incubation showed that SOM content did not statistically increase, but it improved based on the criteria, from very low to low level as OM was applied for ≥ 10 t/ha. It seemed that 10 t/ha Gliricidia sepium was the best dosage at this condition. There was a positive correlation between SOM content and aggregate stability index of Ultisols after fresh Gliricidia sepium addition.Keywords: Ultisols, soil aggregate stability, soil organic matter conten

Physical Characteristics of Ultisols and the Impact on Soil Loss During Soybean (Glycine Max Merr) Cultivation in Wet Tropical Area

Physical characteristicsare among soil propertiesaffecting the susceptibility to erosion. Determination of physical characteristics of Ultisol was aimed to evaluate the dynamics of soil properties as well asthe impact on soil erosion and runoff (RO) during soybean cultivation in wet tropical area. Soybean was planted within erosion plots (18 m2) at 25% slope in UltisolLimauManis (having > 5000 mm annual rainfall). Soil samples for physical properties (soil texture, bulk density, total pore, permeability, aggregate stability,and organic carbon) as well as amount of RO and soil loss were analyzed at 5 different times (stages) during the cultivation. The results showed that there was fluctuation in physical properties of Ultisol during the cultivation. Likewise, the amount of runoff and soil loss also changed during the study. Among the physical properties analyzed, the aggregate stability index of the soil highly correlated to the amount of RO (R2=0.73) and soil loss (R2=0.94). Amount of RO and soil loss was controlled by soybean development at the average rainfall intensity ≤ 36 mm/day, but not at rainfall intensity >36 mm/day. It is suggested not to open heavily clayey-low OC soils for seasonal crop farming during rainy season in wet tropical area

THE EFFECT OF RECLAMATION TO SOIL MOISTURE CONTENT IN THE ROOTING ZONE ON DRY LAND

The critical land reclamation through the conservation farming system could improve the properties of soil such as pore of water available. Thus the land was able to increase the availability of soil water in the zone of rooting annuals. The purpose of the research was to analyze the effect of Reclamation land with conservation farming system to the fluctuation of groundwater in zones rooting annuals. The research method used was an experiment in the field by using the block design in the form of split plot. As the main plot was a conservation tillage system (not reclaimed Ro, reclaimed using mulch R1, reclaiming compost and manure use R2 and reclamation with round up weed R3) and sub plots were the three types of annuals (corn T1 T2 T3, peanuts, and watermelon). Groundwater data monitored using gypsum blocks put in rooting zone about 30 cm in the soil. The soil moisture was measured with ohm meter every day at noon (12.00-13.00). The measured data are calibrated with graphs of soil moisture which has been standard. Then the results are presented in the form of trend graphs of each treatment of the reclaimed land. The research results showed that the fluctuations of the water in the rooting zone higher on land that was not reclaimed (To) than on land reclaimed. Land reclaimed by using compost, manure (T2) tend to be more stable and increases the moisture content of the soi