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The rising shortage of and competition for irrigation water necessitates the adoption of novel measures that promote efficient water application methods. Deficit irrigation is becoming more popular as a means of reducing water consumption without negatively affecting output in the context of improving water use efficiency. At Haramaya University, a field experiment was conducted to investigate the effects of straw mulch levels and deficit watering on the yield components, yield, and water consumption efficiency of hot peppers (Capsicum annum L). Four levels of vetiver straw mulch (0, 3, 6, and 9 tons per ha) and three irrigation levels (100%, 75%, and 50% of ETc) were used in the factorial arrangement of a randomized complete block design with three replications. The experimental plot that got 100% ETc irrigation together with 6 t/ha of straw mulch produced the highest marketable yield (12.36 t/ha), whereas the plots that received 50% ETc irrigation and no mulch produced the lowest yield (4.66 t/ha). Plots received 50% ETc irrigation and 9 t/ha straw mulch, and 100% ETc irrigation and no mulch, respectively, exhibited the highest water consumption efficiency (3.99 kg/m3) and the lowest water consumption efficiency (1.95 kg/m3) values. Water saved, increased area to be farmed and extra yield due to conserved water attained from the plot that was treated with 75% ETc irrigation and 6 t/ha straw mulch were 1148.5 m3, 0.33 ha, and 4.02 tonnes, respectively. Thus, for successful hot pepper production in the research area and other areas with comparable agroecology, irrigating with 75% ETc mixed with 6 t/ha straw mulch may be suggested in terms of marketable hot pepper yield, economically appealing benefit, and water consumption efficiency.

The deteriorating state of soil fertility and low agricultural productivity in Ethiopia can be traced to the lack of equivalent consideration given to the soil's biological, chemical, and physical properties. A pot experiment was conducted to investigate the effect of mixed manure and blended nitrogen, phosphorus, sulfur and boron (NPSB) fertilizer on phosphorus adsorption, and other properties of Vertisols, nutrient uptake, and growth performance of maize. The study findings indicate that the combined application of mixed manure and blended NPSB significantly reduced soil pH from 7.87 to 7.68, phosphorus adsorption efficiency from 93 to 88.5 %, and Freundlich adsorption capacity from 194 to 100.75 mg kg−1 , intensity from 1.96 to 1.27 compared to control. However, combined application of these two treatments significantly increased the organic carbon from 0.81 to 1.64 %, total nitrogen from 0.04 to 0.13 %, and available phosphorus from 6.96 to 73.82 g kg−1. The study further revealed that mixed manure and blended NPSB resulted in significantly (p ≤ 0.05) higher contents of nitrogen and phosphorus in the maize leaves as well as their uptake compared to their sole application and control. The highest values of these parameters were observed in plots treated with a combined application of 15 t ha−1 mixed manure with each rate of 100 and 150 kg ha−1 blended NPSB. Additionally, the maize plant height (p ≤ 0.05) and above-ground biomass (p ≤ 0.01) also exhibited significant increase. Compared to the control and full dose of NPSB, all the treatments that received a combined application of 15 t ha−1 mixed manure with blended NPSB ranging from 50 to 150 kg ha−1 resulted in significantly higher above-ground biomass of maize. The results suggest that the combined use of mixed manure and blended NPSB could be a practical and effective approach to improve soil properties and maize above-ground biomass yield.

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.

Applying inorganic phosphorus fertilizer is less effective in increasing crop yields in tropical soils due to precipitation and adsorption reactions. However, research suggests that partial substitution of organic and inorganic fertilizers has shown to improve the efficiency of applied phosphorus fertilizer by reducing its adsorption and enhancing desorption due to their synergistic effects. This study aimed to investigate the impact of treating the soil with mixed manure (MM) rates and blended nitrogen, phosphorus, sulfur, and boron (NPSB) fertilizer on the soil’s phosphorus adsorption and desorption characteristics. Results showed increased adsorbed phosphorus in all treatments, with increased added phosphorus (P) concentration from 100 to 500 mg kg−1. However, the efficiency of adsorbed P decreased significantly as added P concentration rates increased from 100 to 400 mg·kg−1 in all treatments and then decreased as the added P concentration advanced to 500 mg·kg−1. Moreover, in all treatments that received combined applications of MM and blended NPSB, both quantity and percentage of desorbed P showed a significant increase. The Freundlich adsorption coefficient and constant were also significantly reduced because of the combined application of MM and blended NPSB, compared to the control and their sole applications. Overall, the soil treated with a combined application of 15 t·ha−1 of MM with 100 kg·ha−1 of blended NPSB showed the highest reduction in the efficiency of adsorbed P, percentage of desorbed P, Freundlich adsorption capacity, and intensity by 8%, 37.5%, 60%, and 58%, respectively, as compared to the control. These findings indicate that the combined application of MM and blended NPSB can improve the P availability and uptake by maize by reducing its adsorption while increasing desorption characteristics. Finally, this experiment recommends further research on the long-term effects of MM and blended NPSB on P adsorption and desorption characteristics of vertisols.

Purpose A field study was conducted at Dire Dawa, Eastern Ethiopia, with an objective to find out an optimum combination of inorganic (NP) fertilizer and excreta-based vermicompost for best economic yield and quality of tomato and to assess their effect on selected physicochemical properties of amended soil after crop harvest. Methods The experiment consisted of eight treatments where the mineral (NP) fertilizer and the excreta-based vermicompost were combined in different proportions being arranged in a completely randomized block design replicated three times. Results Growth, yield and quality attributes of tomato as well as the post-harvest soil nutrient status were markedly influenced by the nutrient treatments. The highest values for the various growth, yield and quality attributing parameters were recorded for the treatment combination consisting 75% of the recommended rate of NP fertilizer ? 11.25 ton ha-1 vermicompost (T6), this treatment was also observed to have the highest net benefit with acceptable economic return as well as a fairly high residual soil nutrient status. Following this treatment, is the integration of 50% of recommended rate of NP fertilizer ? 7.5 ton ha-1 vermicompost (T3) which surpassed the sole mineral fertilizer and vermicompost in terms of the cropâs yield and its economic return. Conclusion 25â50% of the recommended rate of chemical fertilizer can be supplemented through vermicompost. However, in order to generate more reliable information, there is a need to conduct more such studies using more integration ratios of these nutrient sources (NP fertilizer and vermicompost) at various soil and agro-climatic conditions.

Abstract The phosphorus (P) fixing behaviors of Vertisols have been identified as one of the key drivers of crop response to fertilizer application. More than 75% of applied P in tropical soil was found to be inaccessible to crops due to adsorption and precipitation reactions. A pot experiment was carried out to investigate the effect of mixed manure (MM) on P adsorption characteristics and other selected Vertisol properties. The soil was amended with 0, 5, 10, and 15 t ha−1 of MM. Changes in selected soil parameters and P adsorption characteristics were evaluated after a 30‐day incubation period. An analysis of variance was used to analyze the data. The results demonstrated a substantial drop in soil pH and an increase in soil organic carbon, total nitrogen, available P, and cation exchange capacity compared to the control. The overall quantity and efficiency of adsorbed P were drastically reduced as a result of MM rates. Moreover, the interaction effect of MM and added P concentration demonstrated a considerable increase in both the quantity and efficiency of adsorbed P. Both parameters increased with increased rates of added P concentration but decreased with increasing rates of MM. Despite the fact that all treatments fit well to both the Freundlich and Langmuir isotherms, the former was used due to its greater R2 value. When compared with the control, the Freundlich adsorption coefficient and intensity were found substantially lower. As a result, MM treatment boosted P availability by decreasing adsorption and associated Vertisols characteristics.

The study was conducted to evaluate the effects of tillage implements and frequencies on selected physical properties of Fluvisols at Haramaya University, Eastern Ethiopia, during the 2013 cropping season. Soil bulk and particle density, total porosity, texture, and soil water retention were analyzed immediately (within 72 hours) and one month after tillage for samples collected from 0-20 and 20-40 cm depths. The experiment was laid out in a split-plot design with treatment combinations consisting of three levels of tillage frequencies (0, 2 and 4) and two tillage implements, oxen-drawn traditional Maresha and disc plows, with three replications. Results indicated that the mean bulk density values were significantly different (P < 0.05) at plow layers (0-20 cm). It ranged from 1.68 g cm-3 for disc plows at two passes to 1.72 g cm-3 for zero tillage and disc plows at four passes one month after tillage at a depth of 21-40 cm. Tillage with a disc plow at increased frequencies decreased total porosity, while oxen-drawn Maresha increased total porosity. Insignificant differences (P < 0.05) in mean values of particle size distribution were observed except for percent clay content immediately after tillage with disc plows at two passes, which showed significant highest mean value (26.30%). Tillage by traditional Maresha resulted in more water holding capacity at increased tillage frequencies. Tillage practice using disc plows at two passes significantly affected the bulk density, total porosity, and soil water retention characteristics. In conclusion, tillage implements and frequencies have shown a negative effect on the physical properties of Fluvisols by disrupting the structure of the soil at surface and subsurface depths, resulting in varying levels of impact on soil bulk density, total porosity, and soil water retention characteristics. Therefore, it is recommended to use the tillage implements at reduced frequencies for less disruption of soil properties while performing soil tilth for agricultural production.

In rice production greenhouse gas emission (GHG) reduction is an important task for many countries, Tanzania included. Of global agricultural GHG emitted from rice fields, about 30 and 11% are represented by CH4 and N2O, respectively. For successful climate smart rice cultivation, rice management practices, including nitrogen fertilization are two key crucial components that need evaluation. The objective of this study was to evaluate the crop management practices and N fertilization on yield and greenhouse gases emission in paddy rice production, Experiments were designed in split-plot randomized complete block and replicated three times. Two rice management practices namely conventional practice (CP) and system of rice intensification (SRI) and six rates of nitrogen fertilizer (absolute control, 0, 60, 90,120 and 150 kg N ha−1) were applied in two consecutive seasons. The Source-selective and Emission-adjusted GHG CalculaTOR for Cropland (SECTOR) was used to calculate the GHG emission. Methane emission was in the range of 88.7–220.6 kg ha−1season−1, where higher emission was recorded in CP treatments (ABC, CP 0 and CP 120N) compared to SRI treatments. SRI reduced methane and carbon dioxide emission by 59.8% and 20.1% over CP, respectively. Seasonal nitrous oxide emissions was in the range of no detected amount to 0.0002 kgN2O ha−1 where SRI treatments recorded up to 0.0002 kgN2O ha−1 emissions while in CP treatment no amount of N2O was detected. The interaction of system of rice intensification and 90 kg N ha−1 (SRI90N) treatment recorded higher grains yield (8.1, 7.7 t ha−1) with low seasonal global warming potential (GWP) (3,478 and 3,517 kg CO2e ha−1) and low greenhouse gas intensity (0.42, 0.45 kg CO2e per kg paddy) compared to other treatments in wet and dry season, respectively. Therefore, SRI with 90 kg N was the treatment with mitigation potential and reduced GWP without compromising rice yield.

Empirical evidence and a better explanation of the effect of exclosures on soil properties are needed to rehabilitate degraded land and properly utilize the restored ecosystem. This study was conducted to determine soil organic carbon (SOC) and total nitrogen (TN) stocks and to map their spatial distribution and aggregate stability along open grazing land, 5, 15, and 20 years exclosure, and three slope positions. To map the spatial distribution of SOC and TN stocks an ordinary kriging interpolation method was applied. The results showed that the age of exclosure had significantly ( p 250 µm) and microaggregates (

This paper examines factors determining farmers’ adoption decision for improved maize varieties in the maize-common bean intercropping practices in two districts of East Hararghe zone, Eastern Ethiopia. It is based on data collected from 129 farm households using structured questionnaire. Descriptive results revealed that adopters of improved maize varieties had better food and nutrition security status. Furthermore, logit model output indicated that the decision to adopt improved maize varieties is influenced by location (district) dummy, education status of the household head, age of the household head, distance from the main road, and the number of plots owned. Major recommendations include improving the rural road infrastructure, educating and training farmers, organizing experience sharing events among farmers, and raising awareness about the food and nutrition security benefits of sustainable agricultural intensification practices like intercropping improved maize with improved common bean varieties.

Abstract Background Soil quality, which can be inferred using indicators that interact synergistically, is affected by land use types and agricultural management practices. This study assessed the status of soil quality under three adjacent land uses (cultivated, grazing, and fallow) in Kersa subwatershed (622 ha). Soil samples were collected from the surface soil (0–20 cm depth) of the identified land uses with three replications and the soil quality parameters were analyzed. A minimum data set of soil quality indicators were selected from physical, chemical, and biological parameters using the literature review and expert opinion method. Linear scoring functions were used to give the unitless scores for the selected data sets, which were then integrated into a soil quality index (SQI). Results The results revealed that bulk density, aggregate stability, pH, cation exchange capacity (CEC), available P, and soil organic carbon (SOC) had a significant difference in SQI among the different land uses. The soil quality indices were 0.69 for grazing land, 0.62 for cultivated land, and 0.59 for the fallow land. The SQI of all the land uses falls in the intermediate soil quality (0.55

AimThis study investigated the impacts of system of rice intensification (SRI) and conventional management practice (CP) on rice growth, grain yield, and nitrogen use efficiency by nitrogen application.MethodsField experiments were conducted in wet and dry seasons; each season, the experiment was set in a split-plot randomized complete block design in triplicate with crop management practices in main plots and nitrogen levels in subplots.ResultsThe average grain yield by SRI was 7.1 and 6.7 t ha−1, while by CP it was 6.1 and 4.4 t ha−1in the wet and dry seasons, respectively. The grain yield of the SRI practice was significantly (p < 0.05) greater than that of the conventional practice (CP) at all levels of nitrogen application. The average yield under the treatment interaction of SRI and nitrogen levels were increased by 13.1% in the wet season and 35.8 % in the dry season. Roots of SRI plants had significantly (p < 0.05) greater fresh weight, length, and volume as indicated by increased root dry weight per hill. SRI improved crop growth, effective tillers, filled grains per panicle, grain filling rate, panicle weight, spikelet per panicle, straw yield, and 1,000-grain weight. Nitrogen application rate had a significant effect (p < 0.05) on agronomic nitrogen use efficiency (ANUE). As the N application rate was increased beyond 90 kg N ha−1, the ANUE and partial factor productivity (PFP) under both SRI and CP were significantly decreased in both seasons.ConclusionOverall, the SRI production system with 60 kg N ha−1 improved rice growth, yield, and nitrogen use efficiency compared to the CP.

Biochar as agricultural soil amendment to improve soil physico-chemical properties, crop productivity and sustainable soil fertility management is a well-known practice. A field experiment was conducted to evaluate the effect of biochar on growth and yield components of carrot and selected soil physic-chemical properties. The study was carried by employing a randomized complete block design with factorial arrangement of four level of biochar (0, 4, 8 and 12 tons ha-1) and four level of Nitrogen/Phosphorus (N/P) fertilizer rate (0/0, 60/10, 90/15 and 120/20 kg ha-1) with four replications. Biochar significantly influenced physico-chemical properties of soils, such as bulk density, total porosity, pH, EC, SOC, TN, Av. P and CEC respectively, as compared to control. The results revealed substantial responses to biochar and N/P fertilization on growth and yield components of carrot with increasing level of biochar and N/P fertilizer rate. None of the others yield parameters were significantly affected by the interaction of two factors. From the present study, it can be concluded that dung cake biochar should be applied to enhance and improve soil physical and chemical properties for favourable plant growth.

Abstract Background Litterfall input and associated nutrient flux are critically important in the restoration of soil in degraded landscapes through exclosures. This study was conducted to evaluate the effects of exclosure on seasonal litterfall production and nutrient content, and estimate annual C and N inputs to the soil in an age sequence at Kewet district, central lowland of Ethiopia. Leaf litterfall production was recorded by a 0.25 m2 litter trap from a systematically laid line transects from 5, 15, and 20 years old exclosures and adjacent grazing land. Results Leaf litterfall input in the exclosures ranged from 37 g m−2 in January (at the old exclosure) to 7.33 g m−2 (at the young exclosure), and 3 g m−2 in March at the grazing land. Litterfall input showed seasonal variation and peaked in the dry months. Mean monthly leaf litterfall production was significantly (p

In Ethiopia, rehabilitation of the natural resource-base in degraded lands through area exclosures has become a necessary intervention, albeit empirical studies on the impact of these exclosures are limited. This study was conducted to investigate changes in selected soil properties along exclosures’ age and slope positions in Kewet district, central dry lowlands of Ethiopia. Soil samples were collected from three slope positions of three purposively selected exclosures of 5, 15 and 20 years old and one adjacent open grazing land from 0-10 cm soil depth for analysis of pertinent soil properties. The effect of exclosure age on bulk density, contents of sand, clay, organic carbon, total nitrogen, available phosphorus, CEC, and exchangeable Mg+ and K+ was significant (P

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.

Abstract Maize (Zea mays L.) is an important food security crop in Ethiopia. However, low soil fertility and the use of haphazard nitrogen (N) fertilizer with little attention to the rate and timing of N application constrain productivity. Therefore, field experiments were conducted during the 2019 and 2020 cropping seasons to investigate the response of maize to different N application rates and timings. The treatments consisted of six N fertilizer rates (0, 23, 46, 69, 92, and 115 kg N ha−1) and four application timings (all at vegetative stages; one‐half at sowing + one‐half at vegetative stages; one‐third at sowing + one‐third at vegetative stages + one‐third at tasseling; one‐fourth at sowing + two‐fourths at vegetative stages + one‐fourth at tasseling). The experiments were a randomized block design in a factorial arrangement with three replications. The results of the study revealed that ears per plant, ear length, grains per row, grains per ear, stover, and grain yield were significantly (p ≤ .001) influenced by the interaction effects of N application rates and timings. The highest stover (9.99 t ha−1) and grain yield (9.41 t ha−1) were obtained from the application of 92 kg N ha−1 in three split applications of one‐fourth at sowing, one‐half at vegetative stages, and one‐fourth at tasseling. Therefore, it is concluded that 92 kg N ha−1 in three split applications of one‐fourth at sowing, two‐fourths at vegetative stages, and one‐fourth at tasseling was found to be the most economical in the study area.

Abstract 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.

Soil acidity is one of the most important environmental threats to the Ethiopian highlands where the livelihood of the majority of people is reliant on agriculture. Yet, information regarding its extent, distribution, causes, and lime requirement at a scale relevant to subsistence farming systems is still lacking. This study (1) investigates the extent and spatial distribution of soil acidity, (2) identifies factors attributing to soil acidification, and (3) predicts the lime requirement for major crops. A total of 789 soil samples were collected from arable lands in the Wolaita area which is mainly characterized by poor soil fertility and soil degradation in southern Ethiopia. Results revealed that the landscape is characterized by a gentle slope followed by strongly sloppy > flat > hilly topographies. Clay is the dominant soil textural class. A soil pH map, which is generated using geospatial analysis, demonstrates that 3.3, 78.0, and 18.7% of the total area were under strongly acidic, moderately acidic, and neutral soil reactions, respectively. The exchangeable acidity (Cmol(+)/kg) varied from nil to 5.1, whereas exchangeable Al ranged from 1.4 to 19.9 Cmol(+)/kg. The soil pH has shown a significantly (p

Abstract Background Though soils in the study areas are characterized by higher iron and aluminum oxides, and low available P contents, study on P adsorption characteristics is limited. The purpose of this experiment was to evaluate adsorption properties of selected soils and determine the standard phosphorous requirements of the soils. In this experiment, separately weighed 2 g soil samples were equilibrated in 50 ml of 0.01 M CaCl2 solution containing KH2PO4 at rates of 0, 1, 2.0, 4.0, 8.0, 16.0, 24.0, and 32.0 mg P L−1. Results The Freundlich model was found to be the best model for the description of the P adsorption characteristics of the soils. The Freundlich coefficient Kf ranged from 123.32 to 315.31 mg P kg−1. The Goha-1 soil had the highest Kf (315.31 mg P kg−1) as Ketasire had lowest Kf (123.32 mg P kg−1) values. The value of SPRf was ranged from 50.50 to 154.02 mg P kg−1 for soils of the study area. Highly significant (P ≤ 0.01) correlation was observed between the Freundlich adsorption parameters and soil physicochemical properties. Conclusion The standard P requirement of the studied soils was higher than the blanket P fertilizer rate recommendations in Ethiopia. Lack of inadequate knowledge about internal and external P requirement of each crop might have decreased yield in the study areas as it could have resulted in under-application of fertilizer P. The presence of high correlation between the adsorption parameters and the soil properties suggested the indices’ prominent role in explaining P adsorption characteristics of the soils. Since higher dose of P is required by soils in the study area because of fixation, alternative P management strategies is needed to reduce P adsorption and enhance P availability.

Soil acidity is a critical issue necessitating urgent attention in most highlands of Ethiopia due to its impact on crop production productivity. Application of organic and inorganic amendments could effectively minimize the problem and improve the fertility level of the soil. Accordingly, a greenhouse experiment was conducted to evaluate the effects of sole and combined applications of lime, FYM, compost and P on soil chemical properties incubated at 20, 40 and 60 days. The treatments were arranged in a completely randomized design with three replications. The results indicated that various treatment combinations raised the soil pH at the 40 days of incubation. All treatments showed increased P availability consistently with increasing time of incubation. Maximum available P was observed at the 60 days of incubation due to application of 8 t FYM ha-1 + 30 kg P ha-1 + 5 t lime ha-1 followed by 8 t compost ha-1 + 30 kg P ha-1 + 5 t lime ha-1. Exchangeable acidity and Al were reduced at the 40 and 60 days of incubation with the application of 30 kg P ha-1 + 10 t lime ha-1 followed by 4 t FYM or compost ha-1 + 15 kg P ha-1 + 10 t lime ha-1. Highest exchangeable Ca was obtained at 20 days of incubation with the application of 30 kg P ha-1 + 10 t lime ha-1 followed by 4 t ha-1 FYM + 15 kg P ha-1 + 10 t lime ha-1. Sole addition of 10 t lime ha-1 elevated ECEC from 19.29 to 22.30 cmolc kg-1 at the 40 days of incubation. Likewise, combined applications of 30 kg P ha-1 + 10 t lime ha-1 improved ECEC of the soil from 19.53 to 24.27 cmolc kg-1 at the 40 days of incubation. Integrated applications of organic and inorganic amendments were found more effective to reduce soil acidity and Al3+ concentration with increasing the fertility of the soil.

Abstract Background Soil acidity and low availability of P are among the major problems limiting crop production in the highlands of Ethiopia. The current study was conducted to evaluate the distribution of chemical P forms and selected physical and chemical properties of soils in Cheha and Dinsho districts, southern highlands of Ethiopia. Twelve representative composite soil samples were collected from the surface layer (0–15 cm) and analyzed for selected soil properties. Analysis of available P and oxalate extractable P, Al and Fe, and P fractionation were done following standard procedures. Results The pH of soils in the study area ranged from 4.65 to 5.45. In the study area the Mehlich-3 extractable P ranged from 8.90 to 25.75 mg kg−1, while the Bray-I extractable P varied from 8.54 to 22.81 mg kg−1. The studied soils had a total P content that ranged from medium to very high. Mehlich-3 P was positively and significantly correlated with pH, CEC and OM, while it was negatively and significantly (P ≤ 0.01) correlated with exAc and exAl. Oxyhydroxides of iron and aluminum were dominating the exchange sites of the studied soils. In terms of the relative abundance of P forms, Res-P and HCl-P followed by NaOH-Po and NaOH-Pi were the dominant P forms in Cheha and Dinsho districts respectively. The total sum of readily available P forms (NH4Cl-Pi, NaHCO3-Pi and NaHCO3-Po) did not exceed 4% of the total P. Conclusion Soils of the study area were acidic in reaction and found to have low available P. Given the presence of considerable amount of total P, low P availability and high soil acidity in the study areas, further research has to be done on adsorption characteristics to determine the P requirements of the soils for better P management.

Abstract Background Potassium (K) availability depends on exchangeable K and relative amounts of other cations. Yet, the latter has mostly been overlooked. Thus, this study was conducted to evaluate availability and spatial distribution of soil K in Nitisols of Wolaita area, southern Ethiopia, with particular regard to emphasis on assessing the potential for magnesium (Mg)-induced K deficiency. About 789 soil samples were investigated and mapped using ordinary kriging method. Results The result showed that 14.8% of the samples were K-deficient based on exchangeable K rating, whereas the K deficiency due to antagonistic effects of Mg was 54%. The spatial analysis also revealed that 68% of the study area (i.e., 57, 120 ha) has shown Mg-induced K deficiency. The finding is against the long belief that soils of the study area and the country contain sufficient quantity of K. Conclusion The findings of this study imply the need for inclusive approach while assessing the K status of soils and also call for greater attention toward K fertilizer intervention that was not in place in the study area. Nonetheless, further study including fertilizer application rates is suggested.

Abstract Background Soil acidity with associated low nutrient availability is one of the major constraints to faba bean (Vicia faba L.) production on Ethiopian highlands. Integrated use of organic and inorganic amendments is believed to reduce soil acidity and improve crop production. Therefore, this field experiment was conducted with the objective of evaluating the effects of lime, mineral P, farmyard manure (FYM), compost and rhizobium in acid soil of Lay Gayint District, northwestern highlands of Ethiopia, in 2016–2017 main cropping season. The experiment comprised twenty sole and combined treatments arranged in a completely randomized block design with three replications. Results Combined application of 8 t FYM ha−1 + 30 kg P ha−1 + 3.6 t lime ha−1 significantly (P

Soil resource information is vital for sound land use planning and sustainable fertility management. This study was carried out with the objective of characterizing and classifying soils of Yikalo Subwatershed at Lay Gayint district, Northwestern Ethiopia. Representative soil pedons were opened along topographic positions and described on genetic horizon basis in the field for their morphological characteristics and analyzed in the laboratory for selected physical and chemical soil properties. The soils were classified following the FAO (2014). The results revealed the presence of variations in the selected morphological properties within a pedon and along the topographic positions. Soils differed in reaction from 4.57 to 6.42. On the surface horizons of the soil pedons, available P content varied from 0.21 to 3.25 mg kg-1, while exchangeable acidity ranged from 0.17 to 3.65 cmolc kg-1 soil. There was no consistent trend for cation exchange capacity (CEC) and PBS (percent base saturation) with soil depth and topographic positions. The soils in Yikalo Subwatershed were classified as Hyperdystric Cambisols (Humic), Haplic Alisols (Humic), Cambic Umbrisols (Colluvic), Haplic Luvisols (Epidystric), and Pellic Vertisols (Mesotrophic). Optimum rates of organic and inorganic amendments should be applied to reduce the level of soil acidity, and improve the fertility level of the soils for better crop production and productivity.

Rice production in Tanzania, with 67% of its territory considered semi-dry and having average annual rainfall of 300 mm, must be increased to feed an ever-growing population. Water for irrigation and low soil fertility are among the main challenges. One way to decrease water consumption in paddy fields is to change the irrigation regime for rice production, replacing continuous flooding with alternate wetting and drying. In order to assess the impact of different irrigation regimes and nitrogen fertilizer applications on growth, yield, and water productivity of rice, a greenhouse pot experiment with soil from lowland rice ecology was conducted at Sokoine University of Agriculture, Tanzania during the 2019 cropping season. The experiment was split-plot based on randomized complete block design with 12 treatments and 3 replications. Water regimes were the main factors comparing continuous flooding (CF) and alternate wetting and drying (AWD) with nitrogen fertilizer levels as the subfactor, comparing absolute control (no fertilizer) with 0 (P and K fertilizers), 60, 90, 120, and 150 kg Nha−1. Alternate wetting and drying (AWD) significantly improved water productivity by 8.3% over CF (p < 0.05). Water productivity (WP) ranged from 0.6 to 1.5 kg of rice per m3 of water. Average water use ranged from 36 to 82 L per season, and water saving was up to 34.3%. Alternate wetting and drying significantly improved yields (p < 0.05) by 13.3%, and the yield ranged from 21.8 to 118.2 g pot−1. The combination of AWD water management and 60 kg N ha−1 nitrogen fertilization application was found to be the optimal management, however there was no significant difference between 60 and 90 kg N ha−1, in which case 60 kg N ha−1 is recommended because it lowers costs and raises net income. Nitrogen levels significantly affected water productivity, water use, and number of irrigations. Nitrogen levels had significant effect (p < 0.05) on plant height, number of tillers, flag leaf area, chlorophyll content, total tillers, number of productive tillers, panicle weight, panicle length, 1000-grain weight, straw yield, grain yield, and grain harvest index. The results showed that less water can be used to produce more crops under alternative wetting and drying irrigation practices. The results are important for water-scarce areas, providing useful information to policy makers, farmers, agricultural departments, and water management boards in devising future climate-smart adaptation and mitigation strategies.

Abstract Background Farmers’ locally have acquired knowledge from generations of experience and experimentation that fit local conditions. Yet, the scientific approach less used farmers’ soil knowledge (FSK) and site-specific soil information. The objectives of this study were to investigate FSK and rationality; to demonstrate how FSK relates to scientifically analyzed soil properties; and to explore the implemented soil management practices and crop performances in selected districts of Wolaita zone, southern Ethiopia. A total of 789 farmers were included, and their fields were evaluated. Data on farmer’s soil nomenclature, soil physicochemical property, soil fertility management practices and crop yield performance were recorded and analyzed. Results Farmers describe and classify their soils using holistic approach. Soil nomenclature and classification indicators are relatively homogeneous over large area. Accordingly, seven soil types common over large area were identified. Mostly, soil types perceived fertile by farmers (e.g., Arrada bita) were found better in measured physicochemical properties than infertile soil types (e.g., Lada bita, Zo’o bita). Simple regression analysis revealed a declining trends of soil properties with a decrease in fertility of farmers soil types such as soil bulk density (r 2 = 0.78), pH (r 2 = 0.53), available phosphorous (r 2 = 0.83), total exchangeable bases (r 2 = 0.71), copper (r 2 = 0.64) and zinc (r 2 = 0.69). Farmers are rational to allocate the scarce fertilizers. They apply more chemical fertilizer when soil type was getting poor in soil fertility (r 2 = 0.61), whereas it was opposite for manure (r 2 = 0.85). Furthermore, crop response and farmers’ soil type also demonstrated an observable relationship where yield was declining with a decrease in fertility level of farmers’ soil types. Conclusions Farmers understand within farm soil variability and exploit soil fertility differences of their field. This is supported with noticeable relationship with scientifically analyzed soil properties, fertility management strategy and crop responses. It suggests that FSK is relevant for site-specific soil management. Yet, FSK is deficient to identify yield-limiting nutrients, implying it has to be complemented with scientific soil knowledge. Additionally, further investigation to systematically link both approaches is also suggested.

Soil is spatially heterogeneous and needs site-specific management. However, soil nutrient information at larger scale in most cases is lacking. Consequently, fertilizer advisory services become dependent upon blanket recommendation approach. Subsequently, it affects yield and profitability. This study is aimed at explaining soil fertility heterogeneity in Wolaita zone, Southern Ethiopia. About 789 soil samples were collected to evaluate soil physical (color, particle size, and bulk density) and chemical properties (pH, OC, N, P, K, Ca, Mg, B, Cu, Fe, Mn, Zn, PBS, and CEC). The laser diffraction method for soil particles and mid-infrared diffused reflectance (MIR) spectral analysis for OC, TN, and CEC determination were employed. Mehlich-III extraction and inductively coupled plasma (ICP) spectrometer measurement were used for the remaining elements. The result based on principal component analysis showed that 52% of the total variations were explained by exchangeable bases, CEC, pH, available P, Cu, B, and particle sizes. Clay texture and acidic soil reaction are dominant. Soil parameters with the following ranges were found at low status: soil OC (0.2–6.9%), total N (0.01–0.7%), available P (0.1–238 mg/kg), S (4–30 mg/kg), B (0.01–6.9 mg/kg), and Cu (0.01–5.0 mg/kg). Besides, low levels of exchangeable Ca, Mg, and K (Mg-induced K deficiency) on 22, 34, and 54% soil samples, respectively, were recorded. The soil contained sufficient Fe, Zn, and Mn. In conclusion, the study aids in developing practical decision for optimum soil management interventions and overcomes lower productivity occurring due to fertilizer use that is not tailored to the local conditions. Overall, continuous cropping, low return of crop residues, and low and/or no fertilizer application might have caused the low status of N, P, K, S, B, and Cu. Therefore, application of inorganic fertilizers specific to the site, lime in acidic soils, and organic fertilizers are recommended to restore the soil fertility and improve crop productivity.

Soil acidity is one of the forms of soil degradation affecting sustainable crop production adversely in the Ethiopian highlands. In order to contribute to soil acidity amelioration and crop productivity improvement on acid soils, an experiment was conducted to investigate the effects of lime, mineral P, FYM, compost, and rhizobium on growth, nodulation, and nutrient uptake of faba bean (Vicia faba L.) in cultivated acid soil under greenhouse conditions. Twenty treatments were tested in isolations as well as suitable combinations. The treatments were arranged in a completely randomized design with three replications. The results showed that application of 8 t FYM·ha−1 + 30 kg P·ha−1 + 5 t lime·ha−1 produced significantly (P

Soil acidity is one of the major factors limiting soil fertility and crop production in large areas of Ethiopia. A two-month incubation experiment was conducted to evaluate the effects of lime, vermicompost (VC), and chemical phosphorus (P) fertilizer on selected chemical properties of Dystric Nitisols in Ebantu District, Western Ethiopia. The treatments comprised of three rates of lime (2, 4, and 6 tons CaCO3·ha−1), VC (2.5, 5, and 7.5 tons·ha−1), and mineral P fertilizer (20, 40, and 60 kg·P·ha−1) each applied alone and in various combinations. The experiment was laid down in a completely randomized design with two replications. The results showed that the highest increment of pH from 4.83 at the control to 6.05 and reduction of exchangeable Al from 1.70 to 0.09 cmolc·kg−1 were obtained from combined application of lime at 4 tons CaCO3·ha−1 and VC at 7.5 tons·ha−1. The most significant decrease in exchangeable acidity (0.17 cmolc.kg-1) was observed in soil that was treated with 6 tons CaCO3·ha−1 lime applied alone (93%) and combined application of lime at 4 tons CaCO3·ha−1 with VC at 7.5 tons·ha−1 by (81%). The highest contents of OM (4.1%) and total nitrogen (0.29%) were obtained from combined application of lime at 4 tons CaCO3·ha−1 and VC at 7.5 tons·ha−1. Integrated application of chemical P (60 kg·P·ha−1) with lime (2 tons·ha−1) plus VC (7.5 tons·ha−1) resulted in Bray-II P increased by 45% relative to control. The various combinations of the treatments also improved exchangeable Ca2+ and Mg2+. The results indicate that integrated use of lime, vermicompost, and chemical P fertilizer can improve soil acidity and availability of nutrients. However, the real potential of the amendments used in this experiment should be further assessed under field conditions using a test crop.

Knowledge of the kinds and properties of soils is critical for making decisions with respect to crop production and other land use types. A field survey and soil morphological description and laboratory analysis were carried out to describe, characterize, and classify the soils of Abobo area, western Ethiopia. Seven representative pedons (A-1 to A-7) were opened and described across the study area. The results revealed variation in morphological, physical, and chemical properties of the soils. The soils are clay loam to clayey in texture with bulk density values ranging from 1.12 to 1.32 g cm−3 and basic infiltration rate varying from slow to moderate (0.4 to 3.3 cm hr−1). They were moderately acidic to neutral in pH (5.5 to 7.1) and had very low to medium organic carbon (OC) (0.27 to 2.98%). Four soil types, Haplic Cambisols, Vertic Luvisols, Mollic Leptosols, and Mollic Vertisols, were identified in the area based on World Reference Base. Generally, the properties of the soils differed along the transect indicating their variation in productive potential and management requirements for specific agricultural use.

Information about the spatial distribution of soil properties is necessary for natural resources modeling; however, the cost of soil surveys limits the development of high-resolution soil maps. The objective of this study was to provide an approach for predicting soil attributes. Topographic attributes and the normalized difference vegetation index (NDVI) were used to provide information about the spatial distribution of soil properties using clustering and statistical techniques for the 56 km2 Gumara-Maksegnit watershed in Ethiopia. Multiple linear regression models implemented within classified subwatersheds explained 6–85% of the variations in soil depth, texture, organic matter, bulk density, pH, total nitrogen, available phosphorous, and stone content. The prediction model was favorably comparable with the interpolation using the inverse distance weighted algorithm. The use of satellite images improved the prediction. The soil depth prediction accuracy dropped gradually from 98% when 180 field observations were used to 65% using only 25 field observations. Soil attributes were predicted with acceptable accuracy even with a low density of observations (1-2 observations/2 km2). This is because the model utilizes topographic and satellite data to support the statistical prediction of soil properties between two observations. Hence, the use of DEM and remote sensing with minimum field data provides an alternative source of spatially continuous soil attributes.

The study was conducted to evaluate the effects of tillage implements and frequencies on selected physical properties of Fluvisols at Haramaya University, Eastern Ethiopia, during the 2013 cropping season. Soil bulk and particle density, total porosity, texture, and soil water retention were analyzed immediately (within 72 hours) and one month after tillage for samples collected from 0-20 and 20-40 cm depths. The experiment was laid out in a split-plot design with treatment combinations consisting of three levels of tillage frequencies (0, 2 and 4) and two tillage implements, oxendrawn traditional Maresha and disc plows, with three replications. Results indicated that the mean bulk density values were significantly different (P ≤ 0.05) at plow layers (0-20 cm). It ranged from 1.68 g cm-3 for disc plows at two passes to 1.72 g cm-3 for zero tillage and disc plows at four passes one month after tillage at a depth of 21-40 cm. Tillage with a disc plow at increased frequencies decreased total porosity, while oxen-drawn Maresha increased total porosity. Insignificant differences (P ≤ 0.05) in mean values of particle size distribution were observed except for percent clay content immediately after tillage with disc plows at two passes, which showed significant highest mean value (26.30%). Tillage by traditional Maresha resulted in more water holding capacity at increased tillage frequencies. Tillage practice using disc plows at two passes significantly affected the bulk density, total porosity, and soil water retention characteristics. In conclusion, tillage implements and frequencies have shown a negative effect on the physical properties of Fluvisols by disrupting the structure of the soil at surface and subsurface depths, resulting in varying levels of impact on soil bulk density, total porosity, and soil water retention characteristics. Therefore, it is recommended to use the tillage implements at reduced frequencies for less disruption of soil properties while performing soil tilth for agricultural production. [ABSTRACT FROM AUTHOR]