Degradation of soil functions in storing and cycling nutrients may be related to topography and land-use change. The research aimed to analyze the impact of land-use changes and slope positions on soil function in nutrient stock within Kalikungkuk micro watershed of East Java, Indonesia. Four different land-uses such as vegetable crops, agroforestry, shrub and forest were selected with three slope positions (e.g. ridge, slope, and valley), and three replications of each. Soil samples were collected at 0-10, 10-30, 30-50, and 50-100 cm depth of soil. Variables measured included soil properties (e.g. bulk density, soil texture, pH, CEC, soil nutrients). Slope positions impact on differences in soil physical (i.e. soil bulk density, soil texture) and chemical (i.e. total N, exchangeable K) properties. In addition, forest conversion to other land-uses (i.e. agroforestry, shrub, vegetable crops) decreased soil nutrient concentration (i.e. total C, total N, Ca, Mg, Na), and consequently resulted in degradation of soil nutrient stocks of especially C and N. The strong positive correlation between soil nutrient stock (e.g. C and N) and vegetation cover such as canopy cover, basal area, and litter (r = 0.63 – 0.78, r table 1% = 0.39) showed the benefit of biodiversity in maintaining soil function on the nutrient stock.

This study aimed to analyze the effect of soil chemical consisting of pH, C-organic, CEC, and base saturation on the production and quality index of Kemloko tobacco varieties, and to identify distribution map of soil chemical properties. The study was conducted by field survey and analysis spatial was used Inverse Distance Weighted interpolation method. The results showed that distribution of soil chemical properties in Tobacco Centers at the Temangung Regency consisting of acidic pH value with a range of values 3,96-6,97, soil C-organic ranges low with a range of values 0,19-6,79%, soil CEC ranges from high to very high with a range of values 10,98-67,84 me/100g -1 , and low base saturation categories with a range of values 13,24-82,77%. Correlation coefficient obtained between the soil chemical properties and tobacco's production; each of them is sequential, i.e., 0,112, -0,204, 0,005, -0,027 in the weak to very weak category. While the level of coefficient correlation between soil chemical properties and tobacco quality index, each of them is sequential, i.e. -0,001, -0,141, -0,175, 0,165 in the very weak category. This was because productivity and quality index of Kemloko tobacco varieties in Tobacco Centers at the Temanggung Regency on 2016 planted season due to high rainfall occurring throughout 2016 on the tobacco processing phase.

Abstract:This research was an attempt to study the impact of forest conversion to intensive rubber plantation on soil characteristics. We selected three landuses (forest, jungle rubber, and rubber plantation) in Bukit Duabelas and Harapan landscape, Jambi, and each repeated three times. Soil profiles were described and sampled at every 10 cm layer to 200 cm depth. Soil bulk density, pH, exchangeable basic cations content, and CEC were determined. The result showed that in three landuses, bulk density is relatively low in the upper 20 cm, but increased with depth. Clay content was lower in forest than other landuses, and increased with depth in forest and jungle rubber. In rubber plantation however, fine clay was accumulated at 60-140 cm depth. The CEC pattern with depth was in accordance to the clay content. There was no significant difference in soil pH between all landuses. In rubber plantation, soil pH was commonly higher in the surface, which probably due to liming activities. Sum of bases decreased with depth and tended to be generally lower in rubber plantation.

The agriculture sector holds an essential role to produce foodstuff, including rice. Malang Regency accomplishes about 0,915% from the total of national rice consumption needed. Any natural factor can influence rice productivity such as the time of sun exposure, where sun exposure at around Malang Regency is equal to 7,5-10,7 hour day-1 based on data from 8 climatological stations. This study aimed at analyzing the influence of time exposure toward rice production potential in Malang Regency. The study consisted of four stages, namely: preparation, pre-survey, survey, and data analysis. Data analysis consisted of correlation and stepwise regression tests. The validation test was carried out to test the feasibility of the observed variables. In addition, a spatial analysis was carried out to determine the distribution of the duration of sun exposure and productivity of rice fields in Malang Regency using ArcGIS 10.3. The results showed that the time of exposure gives a low contribution impact on rice production potential with a correlation value of 0.023. This gives an explanation that there is another factor besides the time of sun exposure that could provide a bigger impact. Surface soil permeability in this research is the only other factor that could influence production potential significantly, with influence level as high as 14.7%. But, result from validation test showed that the p-value obtained is equal to 0.000 (p <0.05), indicating a significant difference between potential production based on the exposure with the results of the field survey, so that the exposure factor still could be used to predicted rice production result in Malang Regency.

Degraded lands are getting extensive worldwide. Even its existence has projected as a solution to fulfill agricultural land scarcity to meet the global demands of food and other agricultural goods, the rate of its extension should be inhibited. Some factors play important role. This research was aimed to find the explanation about how degraded land, biophysical and social factors are related. Research site was located in Lekso Watershed, East Java, Indonesia. Land degradation is assessed by evaluation of the critical land status based on procedure established by Indonesia's Ministry of Forestry in form of Regulation No. P.32/Menhut-II, 2009.A series of field survey using secondary data obtained from GIS tool performed to collect data for quantify the critical land status. Social factors in this study were limited on people perception, awareness and participation. These data collected by in-depth interview to the respondents. Site of presented respondent selected with purposive sampling, while the respondents in each site selected with stratified random sampling method. The research revealed that surface cover demonstrated high correlation and regression toward critical and very critical land (average r =-0.9822, R 2 = 0.9648). However, slope steepness located in high altitude showed a contrary trend in which increasing slope steepness decreased the number of total moderate, critical and very critical lands. The functional area of this location as protected forest gave a good surface cover on the steep slope and resulted on small area of degraded land. On the other side, negative perception about cultivation on forest and steep slope resulted in positive correlations with the area of very critical land (r = 0.6710 for cultivated forest, and r = 0.9113 for cultivated steep slope). Moreover, people awareness about flood, landslide and drought gave a negative correlation (r =-0.6274) with critical and very critical area. At last, people participation on farmers' organization could not be used to elucidate the range of degraded land as the participation in this context did not include the competency building about soil and water conservation values.