This study investigated the effect of different livestock manure composts application on yield, soil chemical properties and carbon sequestration in maize cultivation. The experiment consisted of six different fertilizations; no fertilization (control), chemical fertilizer (NPK), pig manure (PM), NPK + residue of maize (NPKR), NPK + pig manure compost + residue of maize (NPKPR) and NPK + cow manure compost + residue of maize (NPKCR). The yield of maize under NPKPR (5,064.0 kg 10a -1 ) and NPKCR (4,183.7 kg 10a -1 ) were higher than that of NPK (3,775.6 kg 10a -1 ). In soil chemical properties, pH, EC and Avail. P 2 O 5 were increased when livestock compost applied in soil. The content of soil organic carbon (SOC) was higher in order: NPKPR (3.37 g kg -1 ) > NPKCR (3.27 g kg -1 ) > NPKR (3.12 g kg -1 ) > PR (2.88 g kg -1 ) > NPK (2.79 g kg -1 ) > NF (2.48 g kg -1 ). The highest SOC stock was observed in NPKCR (14.67 kg C ha -1 ) due to the high SOC and low bulk density. In conclusion, application of livestock manure composts with inorganic fertilizer increase maize yield, SOC stock. Therefore, it is recommendable for suitable soil management strategy to improve soil fertility and increase crop yield in upland soil. Further study might be required to evaluate long-term compost application effect on soil chemical properties and crop yield.

In this study, we investigated the effect of organic fertilizer application on yield and soil chemical properties for different crops; pepper, garlic, lettuce and zucchini. This study was carried out; 1) to compare crop productivity and relative efficiency of nitrogen (N) under different fertilization level, and 2) to evaluate soil chemical properties during 2 years of cultivation. The organic fertilizer was applied at 50, 100 and 150% level of the pre-plant fertilization rate based on N rate according to soil testing recommendation system. Control treatment was conducted with inorganic fertilization; urea, fused superphosphate and potassium chloride fertilizer. The yields of organic fertilizer treatments were higher than control. And also, relative efficiency of N in organic fertilizer treatments were similar to that of inorganic treatment. Soil properties such as pH, EC and exchangeable cations (K, Ca, Mg, Na) were not significantly different among all treatment, there is no difference between 2 years of experiment. In organic fertilizer application treatments, soil organic matter content showed a tendency of increase compared to inorganic treatment. These results suggest that organic fertilizer application was an effective management strategy to improve crop yield and soil fertility. But, it was short-term monitoring experiment, therefore, long-term experiment is required to evaluate organic fertilizer fertilization impact on crop and soil properties.

Estimation of soil organic carbon (SOC) stocks is highly relevant considering that SOCs is the central driver in soil fertility and climate change mitigation. This study aims to (i) evaluate the SOC stock in the first 0 -30 cm and 0 -100 cm soil layer on a national scale from spatially explicit explanatory environmental variables and a legacy soil database and (ii) the spatial distribution of SOCs at national scale through digital mapping technique. A spatial model was established using Cubist, a decision tree algorithm and based on soil data (s factor), climatic (c factor), topographic (r factor). Results showed that soil texture, soil parent, mean annual precipitatio and elevation were the most important predictors of SOCs. The Cubist prediction model had a Root Mean Squared Error (RMSE) equal to 19.5 at 0 -30 cm, 68.7 at 0 -100 cm. The predicted mean SOC stock from fitted models was 35 ton C ha -1 for 0 -30 cm depth, 87 ton C ha -1 for 0 -100 cm soil depth. In total, soil stored approximately 330 Mt C for 0 -30 cm depth and 842 Mt C for 0 -100 cm depth.