Soil microorganisms are important for the maintenance of soil health and related functions. Agricultural management practices such as land use, season, and fertilizer affect soil microbial community structures. However, the effect of these management practices on soil microorganisms and related functions, influenced by regionally different soil types, is still not clear. Hence, the study was conducted in an Andosol (volcanic soil) dominated agricultural region in a cool temperate climate to determine the effect of land use (cropland, grassland), season (spring, summer), and fertilizer (anaerobic digestate—AD) on soil microorganisms and related functions. Soils were sampled from farmers’ fields, deoxyribonucleic acid (DNA) extracted and sequenced targeting 16S rRNA region. As a result, land use had a significant effect on beta diversity and evenness with higher values recorded in cropland than grassland. However, grassland had a higher number of unique operational taxonomic units (OTUs) (10303) compared with cropland (5112). In cropland, season had a significant effect on beta diversity, evenness, OTU numbers, and Shannon index with higher values recorded in summer compared to spring. Based on predicted soil functions, nitrogenase (nifH) had significantly higher values in cropland‐summer while nitrite reductase (nirK) and ammonia monooxygenase (amoA) were significantly higher in cropland‐spring. In grassland, season had a significant effect on beta diversity only. These results indicate that grassland microorganisms were stable and more resistant to seasonal changes than cropland, suggesting that conventional tillage practices have a negative effect on soil microbial stability. Additionally, grassland‐spring (7059) had a higher number of unique OTUs than grassland‐summer (2597). Based on predicted soil functions, nifH was significantly higher in grassland‐spring while nirK and amoA were significantly higher in grassland‐summer. These results indicate that the impact of seasons on soil microorganisms’ distribution and abundance in cropland and grassland may directly affect soil functions.

No abstract

No abstract

No abstract

Biochar application to legume-based mixed cropping systems may enhance soil microbial diversity and nitrogen (N)-cycling function. This study was conducted to elucidate the effect of biochar application on soil microbial diversity and N-cycling function with a particular focus on legume species. Therefore, we performed a pot experiment consisting of three legume species intercropped with maize: cowpea, velvet bean, and common bean. In addition, one of three fertilizers was applied to each crop: biochar made of chicken manure (CM), a chemical fertilizer, or no fertilizer. Amplicon sequencing for the prokaryotic community and functional prediction with Tax4Fun2 were conducted. Under the CM, Simpson’s diversity index was higher in soils with common beans than those in other legume treatments. On the other hand, N-cycling genes for ammonia oxidation and nitrite reductase (NO-forming) were more abundant in velvet bean/maize treatment, and this is possibly due to the increased abundance of Thaumarchaeota (6.7%), Chloroflexi (12%), and Planctomycetes (11%). Cowpea/maize treatment had the lowest prokaryotes abundances among legume treatments. Our results suggest that the choice of legume species is important for soil microbial diversity and N-cycling functions in CM applied mixed cropping systems.

No abstract

No abstract

The current study, conducted in semi-arid Machakos and Kitui Counties of Kenya, simulated effect of climate change (CC) on finger millet yield under different soil fertilizer inputs (SFI), tillage practices (TP) and projected CC scenarios using the Agricultural Production Systems Simulator (APSIM) model. A randomized complete block design with split plot arrangement was employed. Main plots were TP; oxen plough-OP, ridges and furrows-RF with SFI; Farm yard manure-FYM, Triple super phosphate-TSP + Calcium Ammonium Nitrate-CAN (TSP+CAN) and no fertilizer input as splitplots. The CC scenarios considered were; Current Rainfall (R0) and Temperature (T0) provided the baseline, R1 (R0+10% increase in rainfall), R2 (R0-10% decrease in rainfall), T1 (T0 + 20C) and T2 (the combined effects of 10% decrease in rainfall and 20C increase in temperature (-10%+20C). Significantly (P≤0.001) higher finger millet yields were obtained in TSP+CAN treated plots compared to FYM and control in both Kitui (with higher yields) and Machakos. Comparatively, finger millet yields were well simulated with moderate RMSE (1.04, 0.94) values in OP and RF in Kitui and low values (0.18) in OP in Machakos). Simulated finger millet yields mirrored measured yields, and were higher in Kitui (RF) than Machakos (OP) with TSP+CAN recording highest simulated yields compared to FYM and control. R1 (R0+10% rainfall) registered significantly high finger millet yields under OP and RF with application of TSP+CAN in both sites. The lowest finger millet yields, across sites were noted in T2 (-10% rainfall+2 0 C), in decreasing order; TSP+CAN; FYM and control under OP and RF. Finger millet yields measured and simulated, insitu and across CC scenarios, indicated that application of TSP+CAN under conservation tillage practices (RF in Kitui and OP in Machakos) consistently gave superior yields compared to FYM and control. In the event of change of climate favouring increased rainfall (R1), finger millet grown under RF and OP with application of TSP+CAN may have the potential to adapt to climate change and enhance food and nutritional security. Further studies, mainly focusing on moisture conservation and breeding of drought tolerant crops, are nonetheless recommended to generate possible CC adaptation strategies under R2, T1 and T2 possible climate change scenarios in semi-arid regions of Kenya.