Biochar and sewage sludge phosphorus fertilizer effects on phosphorus bioavailability and spinach ( Spinacia oleracea L.) yields under no-till system in semi-arid soils

Purpose This field study evaluated the interactive effects of biochar (BC) and sewage sludge (SS) on P bioavailability and spinach yields for two seasons.Method Treatments were combinations of biochar (0, 2.5 and 5 Mg ha-1) and sewage sludge (0, 6 and 12 Mg ha-1), or mineral fertilizer (200, 28, and 18.9 kg ha-1), amended in a randomized complete block design to Luvisol and Cambisol.Results Significant (p 0.05) yields compared to sole amendments. Mehlich – 3 extractable P (M3-P) in control plots (CONT) increased between seasons, presumably due to P inputs from the irrigation water. Co-amendments on the Cambisol resulted in higher M3-P increase over mineral fertilizer than on the Luvisol in both seasons. Accumulation of M3-P in control plots confounded correlations between crop yields and available P. Higher P under BC compared to SS amended soils emphasize biochar capacity to capture P from irrigation water.Conclusion The results suggest that combined low rates of SS and BC can have significant effects on P availability and crop yields. Biochar enhanced plant P uptake, but decrease in yields with simultaneous increase in M3-P between seasons warrants further research

The Role of Poultry Litter and Its Biochar on Soil Fertility and <i>Jatropha curcas</i> L. Growth on Sandy-Loam Soil

Low agricultural output and a decline in plant-available nutrient content in soil pose significant challenges to developing countries. To test the hypothesis that poultry litter and its biochar improve soil quality, nutrient status, and plant growth, a greenhouse pot experiment with sandy-loam soil was conducted. Selected application rates of poultry litter (0, 15, 30, 60, and 120 g/kg) and its biochar pyrolyzed at 350 °C and 600 °C were used. With the addition of organic amendments, Jatropha plant height, leaf number, and stem diameter improved significantly, as did soil fertility indicators (pH, organic matter content, cation exchange capacity, and plant-available nutrients). When compared to the control, increased application rates ranging from 60 g/kg to 120 g/kg significantly improved soil properties and plant growth. PL (Poultry litter)- and BC350 (Biochar produced at 350 °C)-treated soil outperformed other organic amendments in terms of soil quality, nutrient status, and plant growth. Soil pH, CEC, and OM were found to be positively correlated with available plant nutrients, with PL-treated soils having higher levels of plant available nutrients. Because the properties of the feedstocks complement each other, combined organic amendments improved studied parameters, particularly PLBC600 (Poultry litter mixed with biochar produced at 600 °C) compared to BC600 (Biochar produced at 600 °C). Increased application rates of pure and combined feedstock effectively increased soil fertility and Jatropha growth; however, lower temperature biochar is recommended for use as a soil organic amendment

Analysis of the long-term agricultural drought onset, cessation, duration, frequency, severity and spatial extent using Vegetation Health Index (VHI) in Raya and its environs, Northern Ethiopia

Abstract Background Droughts cause serious effects on the agricultural and agro-pastoral sector due to its heavy dependence on rainfall. Several studies on agricultural drought monitoring have been conducted in Africa in general and Ethiopia in particular. However , these studies were carried out using the limited capacity of drought indices such as Normalized Difference Vegetation Index (NDVI), Vegetation Condition Index (VCI), and Deviation of Normalized Difference Vegetation Index (DevNDVI) only. To overcome this challenge, the present study aims to analyze the long-term agricultural drought onset, cessation, duration, frequency, severity and its spatial extents based on remote sensing data using the Vegetation Health Index (VHI) 3-month time-scale in Raya and its surrounding area, Northern Ethiopia. Both the MOD11A2 Terra Land Surface Temperature (LST) and eMODIS NDVI at 250 by 250 m spatial resolution and hybrid TAMSAT monthly rainfall data were used. A simple linear regression model was also applied to examine how the agricultural drought responds to the rainfall variability. Results Extremely low mean NDVI value ranged from 0.23 to 0.27 was observed in the lowland area than mid and highlands. NDVI coverage during the main rainy season decreased by 3–4% in all districts of the study area, while LST shows a significant increase by 0.52–1.08 °C. VHI and rainfall value was significantly decreased during the main rainy season. Agricultural drought responded positively to seasonal rainfall (R2 = 0.357 to R2 = 0.651) at p < 0.01 and p < 0.05 significance level. This relationship revealed that when rainfall increases, VHI also tends to increase. As a result, the event of agricultural drought diminished. Conclusions Remote sensing and GIS-based agricultural drought can be better monitored by VHI composed of LST, NDVI, VCI, and TCI drought indices. Agricultural drought occurs once in every 1.36–7.5 years during the main rainy season, but the frequency, duration and severity are higher (10–11 times) in the lowland area than the mid and highlands area (2–6 times) during the last 15 years. This study suggests that the effect of drought could be reduced through involving the smallholder farmers in a wide range of on and off-farm practices. This study may help to improve the existing agricultural drought monitoring systems carried out in Africa in general and Ethiopia in particular. It also supports the formulation and implementation of drought coping and mitigation measures in the study area

Land Use and Land Cover Change Determinants in Raya Valley, Tigray, Northern Ethiopian Highlands

Land use and land cover change (LULCC) is the result of both natural and socio-economic determinants. The aim of this study was to model the determinant factors of land cover changes in Raya Valley, Southern Tigray, Ethiopia. Multistage sampling was used to collect data from 246 households sampled from lowlands (47), midlands (104), highlands (93), and sub-alpine (2) agro-climatological zone. Descriptive statistics and logit regression model were used to analyze the field survey data. Agricultural land expansion, fuelwood extraction, deforestation, overgrazing and expansion of infrastructure were the proximate causes of LULCC in the study area. Agricultural land expansion (p = 0.084) and wood extraction for fuel and charcoal production (p = 0.01) were the prominent causes for LULCC. Persistent drought (p = 0.001), rapid population growth (p = 0.027), and climate variability (p = 0.013) were the underlying driving factors of LULCC. The determinants of LULCC need to be considered and mitigated to draw robust land use policy for sustainable land management by the smallholder farmers. This study provides important results for designing and implementing scientific land management strategies by policy makers and land managers

Comparison of internal standard and standard additions calibration procedures for the determination of selected heavy metals in treated municipal effluent by MP-AES

We compared the internal standard calibration and standard additions calibration methods in the determination of Cd, Cr, Fe, Mn, Pb and Zn in municipal effluent using microwave-induced plasma atomic emission spectrometer. Comparison was based on validation parameters such as linearities, linear ranges, limits of detection (LOD), precisions and recoveries obtained using both calibration methods. Both methods gave good linearities applicable to a simple linear regression data fitting. Severe loss of linearity was observed at levels beyond 3 mg/L particularly for Zn. Considering this, the compromise linear range for all target analytes was established at LOD–3 mg/L. While the LODs for the target analytes were sufficiently low for both methods, the internal standard method was found to be more sensitive compared to standard additions method. Thus, the optimal linear ranges were accurately established at 0.24–0.96 mg/L for the internal standard and 1.10–1.96 mg/L for the standard additions method. Analyte recoveries including for the certified reference material averaged ∼ 100%. Therefore, all target analytes with the exception of Cd, which was possibly below the method detection limit were confidently detected and accurately quantified in municipal effluent samples. Overall, the excellent quantitative data obtained in this study inferred a high level of confidence in the developed methods in that they differed by less than 10%. Indisputably, the performance of the MP-AES operated in internal standard- and standard additions modes have proved to be a sufficiently sensitive technique especially for heavy metals occurring at sub-ppm levels

Analysis of drought coping strategies in northern Ethiopian highlands

Abstract One of the most detrimental concerns brought on by a changing climate that annually affects many people's lives is drought. Proactive and reactive drought coping and adapting mechanisms enable farmers to be resilient against climate–induced drought and improve the drylands' current disaster preparedness and early warning systems. The aim of this study was to assess proactive and reactive farmers' drought coping strategies at household level in Raya Valley in southern Tigray, Ethiopia. Agro–climatological based 246 households were sampled from the lowlands, midlands and highlands of the study area. The most effective drought coping mechanisms were discovered using a multinomial logit model. The study area had endured mild to extremely severe drought in the last three decades. The association between the various drought severity and household heads were significant (chi2 = 9.861, df = 3, p < 0.05). Proactive drought coping measures included collecting and storing pasture, conserving soil and water, weather prediction information to adjust saving and farming practices. Livestock feeding with roasted cactus cladode, small business loans, livestock selling, productive safety–net program, and food consumption reduction were the major reactive drought coping strategies. The proactive and reactive drought coping strategies identified in this study should be used to improve the existing disaster preparedness and early warning systems in the face of climate and weather extreme related impacts of climate variability and change