Effects of natural and modified zeolite based composite fertilizers on slow release and nutrient use efficiency.

Excessive use of chemical fertilizers causes serious environmental hazards, as only a fraction is really adsorbed by the soil. As part of the solution, the feasibility of using unmodified (UNZC) and surfactant-modified natural zeolite-based composite (SMNZC) fertilizers as support materials for the provision of nutrients to soil on a slow release basis was assessed using column and pot experiments. The characterization of the zeolite materials was done using powder XRD, XRF, SEM, BET, and TGA instruments. The percentage of cationic nutrients released from soil columns containing UNZC increased over time. Their release from SMNZC initially slowed down and became stable as the number of days increased. The percentage of N-NO3- and available P released from UNZC has constantly decreased with time. Their release from SMNZC increased as the number of days increased. The maximum P uptake by maize was observed for the soil treated with SMNZC, and there was no significant difference at all rates. The maximum uptake of Ca (3663.40 ppm), Mg (2617.34 ppm), and Fe (222.83 ppm) was observed at 250 kg/ha of UNZC. The highest uptake of K, Zn, and Cu was also observed for the soil amended with UNZC, irrespective of its application rate. Application of UNZC and SMNZC at the same rate equally affected total nitrogen uptake. Thus, this finding showed that UZNC is a better carrier of cationic nutrients, while SMNZC is preferable for the slow release of NO3- and available P. In conclusion, both the modified and unmodified support forms showed better performance than conventional fertilizer in delivering nutrients slowly and sustainably.

Land use and land cover dynamics and ecosystem services values in Kewet district in the central dry lowlands of Ethiopia.

A better comprehensive and quantitative analysis of the tempo-spatial dynamics of land use and cover (LULC) in the dry lowlands areas of Ethiopia is crucial for restoring degraded landscapes. This study aimed at analyzing the trends of LULC changes and determine their ecosystem service values in Kewet district central dry lowlands of Ethiopia using multi-temporal satellite imagery for three periods: 1995, 2008, and 2017. Supervised classification, using the maximum likelihood classifier, was applied to quantify LULC changes. Ecosystem Service values were estimated using the modified ecosystem service value coefficients. LULC analysis showed that cultivated land was the most predominant which covered over 41% of the study area in all three periods. Forests showed a net increase of 18.2%. Shrubland occupied the second largest portion in all LULC analysis next to cultivated land, and it showed a net decrease of 29.2%. Open grassland showed a periodic increase. Over the past 20 years, built-up area and bared land grew continuously by 1.80 and 1.01 km2 yr-1, respectively. However, some degraded land was converted into woody vegetation land through area exclosure, which improved the vegetation coverage of the study area. Ecosystem Service values ranged from US$ 2.37 million for shrubland in 1995 to US$ 22.49 million for forest land in 2008. The total ESVs of the district also continuously decreased over the past two decades. Generally, the LULC in the Kewet district has been dynamic in that some of the LULC classes were expanding, while the others were shrinking through time.

Lowering nitrogen rates under the system of rice intensification enhanced rice productivity and nitrogen use efficiency in irrigated lowland rice.

Among the essential plant nutrients, nitrogen (N) is the most important and universally deficient in rice cropping systems worldwide. Despite different practices available for improvement of N management, nitrogen use efficiency (NUE) is still very low in rice, particularly under conventional management practices. This study was conducted to assess the effect of two crop management practices including the system of rice intensification (SRI) versus conventional management practices (CP) with four N application levels (60, 90, 120, and 150 kg N ha-1) and absolute control (i.e., without N application) on rice growth, grain yield, and NUE. Experiments were established in split-plot randomized complete block design in three replicates. Crop management practices and N levels were treated as the main effect of main-plots and sub-plots, respectively with replicate blocks treated as random factors. Results indicated that deploying of SRI increased rice grain yield by 17.5 and 52.4% during wet and dry seasons, respectively compared with the CP. Rice grain yield was significantly (p < 0.05) higher in SRI than in CP at all levels of N application compared. The application of N at 120 and 60 kg ha-1 resulted in the increase in rice grain yields by 49 and 46.5%, respectively, relative to the absolute control during wet and dry seasons. Nitrogen application had a significant effect (p < 0.05) on agronomic nitrogen use efficiency (ANUE) and partial factor productivity (PFP). Results also indicated that agronomic nitrogen use efficiency (ANUE) was higher (27.2 kg grain kg-1 N) during the wet season with an application of 60 kg N ha-1. Furthermore, higher ANUE (23.8 kg grain kg-1 N) was recorded during dry season with an application of 90 kg N ha-1. The significant (p < 0.05) interaction effects of treatments were recorded on PFP between SRI and 60 kg N ha-1 during the wet (116.7 kg grain kg-1 N) and dry (105.8 kg grain kg-1 N) seasons. This study revealed that ANUE and PFP decreased with N application at the levels of 120 and 150 kg N ha-1 under SRI and CP during the two cropping seasons. The findings of the present study provide potential information that rice grain yield and higher NUE could be achieved at low N inputs under SRI, and thus reducing costs resulted from fertilizer inputs without compromising other environmental benefits.

Carbon stock under major land use/land cover types of Hades sub-watershed, eastern Ethiopia.

BACKGROUND: Developing land management scenarios that have the potential to sequester carbon and reduce greenhouse gasses (GHG) emission on a sustainable basis entails quantifying the current carbon stock under different land uses. In light of this, a study was conducted in Hades sub-watershed, eastern Ethiopia, to explore the carbon stock under four major land uses: natural forest, coffee agroforestry, grazing land and cropland, involving samples from four carbon pools: aboveground, belowground, litter, and soil. To this end, vegetation and soil samples were collected from the respective land uses following recommended procedures. RESULTS: The results indicate that organic carbon concentration decreased with soil depth though substantial amount of carbon was found in the lower soil depths under land use with woody perennials. The mean total organic carbon stock ranged from 138.95 t ha-1 in the cropland to 496.26 t ha-1 in the natural forest. The soil organic carbon stock was found to be relatively higher than that of the vegetation carbon stock in the natural forest and coffee agroforestry land uses. CONCLUSION: This study highlights the importance of assessing watershed level carbon stock for better and carbon friendly land use decision making. Land uses with woody perennials have high carbon stock than those without. Hence, conservation-based production systems with inclusion of woody perennials are options suggested to enhance carbon sequestration in the sub watershed.