Purpose An 8-week incubation study was conducted to monitor soil inorganic nitrogen (N), dissolved organic carbon (DOC), greenhouse gases (GHG) [CO 2 , N 2 O and CH 4 ] and cumulative global warming potential (GWP) in dryland soil. Methods Soil was amended with variable rates of compost (zero, 15, 30 and 45 dry Mg ha −1) and soil moistures [5% (dry), 7% (normal) and 14% (wet) water filled pore space (WFPS)] and experienced biweekly temperature transitions from 5 °C (late winter) to 10 °C (early spring) to 15 °C (late spring) to 25 °C (early summer). Results The addition of 30 and 45 Mg ha −1 compost enhanced N mineralization with 13% more soil inorganic N (7.49 and 7.72 µg Ng −1 day −1 , respectively) during early summer compared with lower compost rates. Normal and wet soils had 35% more DOC in the late spring (an average of 34 µg g −1 day −1) compared to the dry WFPS, but transitioning from late spring to early summer, DOC at all soil WFPS levels increased. Highest rates of compost were not significant sources of GHG with normal soil WFPS, compared with lower compost rates. Carbon dioxide emissions increased by 59 and 15%, respectively, as soil WFPS increased from dry to normal and normal to wet. Soils with normal WFPS were the most effective CH 4 sink. Conclusion One-time application of high compost rates to dryland soils leads to enhanced N and C mineralization under normal soil moisture and warmer temperature of the summer but will not pose significant global warming dangers to the environment through GHG emissions since soils are rarely wet.

Intensification of staple food crops such as Yam (Dioscorea spp.) while sustaining the environment is imperative in providing food for the expected 9.6 billion global population by 2050. In West Africa, amid the threat posed by climate change on food security, yam production is associated with deforestation and land degradation. Integrated soil fertility management and improved staking options for intensification and sustainable yam production on continuously cropped fields hold the key to addressing this challenge. This review evaluates the last decade's yam production trends in West Africa and in three leading yam-producing countries, Nigeria, Ghana, and Côte d'Ivoire, using the Food and Agriculture Organization Corporate Statistical Database (FAOSTAT) data. A production increase of 1.72, 1.43, and 1.35 times resulted in an area harvest increase of 2.25, 1.23, and 1.59 times in Nigeria, Ghana, and Côte d'Ivoire, respectively. Nigeria and Côte d'Ivoire had the worst yam productivity across the decade by producing at an average yield 17.3 and 12.5%, respectively, of the estimated potential yam yield (50 t ha−1). Even in Ghana, where the productivity increased across the decade, the average productivity was 33% of the estimated potential yield. Thus, it can be observed that the primary reason for the increase in yam production across the globe and in West Africa is mainly because of the increase in area under cultivation in the major yam-producing countries. The projected future erratic rainfall and elevated daily mean temperature as a result of climate change would cause declining tuber yields. Meanwhile, the importation of food such as rice as a strategy to improve food availability cannot be accessed by poor rural households due to the strong correlation between international food price hikes and prices of these foods. However, there is less relationship between international yam price hikes and yam prices in West Africa. Therefore, yam production and sustenance could be vital for food security for the increasing population of West Africa. This study reviews current research on soil fertility and staking options for sustaining yam production on continuously cropped fields. Promotion and adoption of these improved technologies would enhance food security and contribute to achieving Sustainable Development Goals 1 (No poverty), 2 (Zero hunger), 13 (Climate action), and 15 (Life on land).

Organic fertilizers with low C:N ratios can be applied to supply both macro and micronutrients to the soil. Aside nutrient supply, they can improve soil structure, texture, water holding capacity and nutrient holding capacity. The mechanisms that may interplay to allow organic fertilizers to affect the soil and crop yields may include improved nutrient synchrony, general improvement in fertility and/or priming effects. The rate, timing and method of organic fertilizer application must be considered to reduce N and P losses during organic fertilizer application. To meet the nutrient requirement of crops, organic fertilizers must be applied in large quantities, so it is more prudent to apply locally available resources. In a case study where sole organic fertilizer, sole inorganic fertilizer and their combinations were applied under rain-fed conditions, it was observed that manure had the potential to hold nutrients longer. This is a positive finding for drought prone areas.

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Aims: This study was conducted to enhance the tolerance of common beans to drought events occurring at the reproductive stage, from a soil improvement perspective. Study Design: Split plot completely randomized design was used. Place and Duration of Study: Study was conducted in a screen-house at the Legumes and Oil Seeds Division of CSIR-Crops Research Institute, Ghana, from September 2021 to January 2022. Methodology: Municipal Solid Waste Compost and inorganic fertilizer combinations were applied to common beans in a pot experiment. They included control, full rate compost (FRAC), full rate fertilizer (NPK 5:30:30 kg/ha) (FRG), FRG + half rate compost (HRAC) and FRG + FRAC. All soils were maintained at 80% field capacity (FC) from the start of the experiment. At flowering, two groups of plants were water stressed till 40 and 16% FC and returned to 80% FC till physiological maturity, while one group maintained 80% FC throughout study. Forty-five soil samples each and plant data were collected at 3, 7 and 10 weeks after planting. Samples were analyzed for soil organic matter (SOM) and water retention, soil nutrients, crop growth, yield and nutrient uptake. Water and nitrogen use efficiencies (W/NUE) were calculated after harvest. Results: During the growing period, highest soil moisture (6-9 cm3/cm3) was retained by FRG and FRG+HRAC, FRG+FRAC; 20-38% more than FRAC and control but was not influenced by SOM. While FRG influenced the highest yield and WUE, combining it with compost rates reduced yield by 56-84% and WUE by 55-64%. WUE correlated positively with NUE. Conclusion: Antagonistic effect observed with integrating compost with FRG is likely because compost was not properly cured and immobilized soil nitrogen. Farmers can mitigate short-term drought effects on common beans with adequate nutrient supply through fertilizer application; however, fertilizer should only be integrated with compost after compost quality analysis.

A field experiment was conducted at Kpongu in the Upper West region of Ghana to determine the added benefits in grain yield of maize derived from the concurrent use of manure and mineral fertilizer, and their cost effectiveness. Factorial combinations of cattle manure and mineral fertilizer each at 0, 50 and 100% of their recommended rates were evaluated in both the field and the laboratory studies. The treatments were applied in a randomized complete block design with three replications on the field. The same treatments were applied in the incubation study in a completely randomized design. The use of 100% NPK (Nitrogen, Phosphorus, Potassium) + 5 t manure gave the highest grain yield of 4,678 kgha -1. Synergistic interactions resulting in added benefits in grain yield were observed in all the combined nutrient inputs except 50% NPK + 2.5 t manure which accrued an added disadvantage of 44 kgha -1. Economic analysis proved that 100% NPK + 2.5 t manure and 50% NPK + 5 t manure were the most economically viable combined treatments in terms of grain yield. Based on the results from this study, resource poor farmers in the Upper West region of Ghana may reduce mineral fertilizer recommended rates by 50% and supplement it with 5 t quality (N >2.5%) cattle manure without compromising yield and profit.

Aims: One-time high rates of compost were applied at 15, 30, and 45 Mg ha-1 to improve soil organic matter (SOM) and fertility in dryland organic winter wheat-fallow rotations. Cover crop mixtures (oats and Austrian winter peas) were planted in fallow phases annually to suppress weeds and reduce repetitive tillage used for weed control because the latter breaks down SOM. Study Design: The experiment was laid-out in a split-plot design with four replications. Fertilizer (compost rates, inorganic fertilizer and no amendment control) and cover crops served as main and sub-plot factors respectively. Place and Duration of Study: The experiment was conducted at the Sustainable Agriculture Research and Extension Center, University of Wyoming, from September 2015 to August 2018. Methodology: Soil samples, weed biomass, wheat yield and protein quality data were collected and analyzed over three years. Results: Results indicated that 45 Mg ha-1 compost increased (P=.05) soil total carbon (TC) and nitrogen (TN) concentrations up to 25 and 19% respectively, in the last two years. Wheat yield was not affected (p>0.05) by compost or cover crops in any growing season but 45 Mg ha-1 compost increased (P=.05) protein quality by 2-9% in the first growing season. Cover crops suppressed weeds while growing in the first growing season but had varying effects on weeds in wheat phases that followed them in rotation. It was noted that soil electrical conductivity levels affected by 45 Mg ha-1 compost was 5 times lower than wheat thresholds; and soil moisture loss by cover crops did not affect wheat yield. Conclusion: 45 Mg ha-1 compost improves soil fertility and SOM in the short term. However, significant reflection of soil changes in wheat yield may take longer time. Further research is needed to effectively integrate cover crops as a weed control measure in dryland organic wheat-fallow rotations.

In dryland organic winter wheat-fallow rotation systems of U.S. Central High Plains, the usual practice of 10–15 Mg/ha compost application every 3–4 years, has not yielded desired soil organic matter (SOM) improvements. One-time high rate compost application and annual cover crop planting (instead of repetitive tillage) to control weeds have been proposed for carry-over SOM improvement in these systems. In this study, 15, 30 and 45 Mg/ha compost rates and controls (‘no amendment’ and inorganic fertilizer) were considered. One-half of fallow blocks were planted to cover crop mixtures. SOM indices: soil nitrate (NO3−), ammonium (NH4+), dissolved organic C/N (DOC/N), potential mineralizable N (PMN), carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions, and soil moisture were measured bi-weekly across three winter wheat growing seasons. The 45 Mg/ha compost affected 25–35% more NO3− in the first growing season; 27–70%; 8–49%; 12–44% more DON, PMN, DOC and 25–57% less CO2 in the second growing season; but did not worsen global warming potential in any growing season. In the fallow phases, cover crops depleted 10–14% soil moisture in the first two growing seasons, which was recovered by precipitation in succeeding wheat phases. Cover crops utilized 21–46% soil NO3− in these growing seasons which reduced N2O emission by 26%. The 45 Mg/ha compost improved SOM and ensured environmental quality, but annual cover crop biomass (< 2000 kg/ha) did not add significant SOM. Therefore, integrating larger biomass producing cover crops with 45 Mg/ha compost in wheat-fallow rotations may be a better prospect.