This study assessed the soil organic C (SOC) and soil nutrients in smallholding home garden, woodlot, grazing land, and cropland at two soil depths and two sites in Wolaita Zone, southern Ethiopia. The results showed that soil properties were significantly influenced by land use. The home garden had significantly higher (p < 0.05) SOC and soil nutrients when compared to the cropland. When the home garden was compared to the woodlot and grazing land uses, it had significantly higher (p < 0.05) values except in SOC, total N (TN), cation exchange capacity (CEC), and exchangeable Ca. Cropland, in comparison with grazing land and woodlot, had a non-significant difference except TN. The SOC stock (0-40 cm) in the home garden, woodlot, grazing land and cropland was 79.5, 68.0, 65.0, and 58.1 Mg ha -1 , respectively. Home garden significantly differed (p 0.05) in SOC only from cropland, and this was attributed not only to the relatively higher organic input in the home garden but also to the little organic matter input and frequently tillage of the cropland. The similar SOC among the home garden, woodlot and grazing lands may imply that the balance between inputs and outputs could be nearly similar for the land uses. Soil TN and CEC had a nearly similar pattern of difference as in SOC among the land uses because of their close relationship with SOC. In general, the land use influence on soil nutrients can be in the order: home garden > wood land grazing land cropland, with home garden showing the least difference from the woodlot and the greatest from the cropland. In the agroecosystem, in general, the influence of smallholding home garden on SOC and soil nutrient was marginally different from Eucalyptus woodlot and grazing lands but evidently different from cropland.

No abstract

Purpose. This study evaluated the P sorption characteristics of soils under smallholding land use in Wolaita Zone, Southern Ethiopia. Methods. Soil samples (0–20 cm) were collected from each of the home garden, grazing land, cropland, and woodlot in three replications at two sites and analyzed for P sorption isotherm data and selected soil properties. Results. The P sorption data were generated by equilibration with P solutions and the data were fitted with the Freundlich model (r2 = 0.88–0.98, SE = 0.16–0.24) and Langmuir model (r2 = 0.81–0.98, SE = 0.45–1.71). The Langmuir P sorption maximum (Qmax) and Freundlich sorption coefficient (Kf) were the highest in the cropland soils while these parameters were the lowest in the home garden. Maximum buffering capacity (MBC) was in the order cropland > woodlot > home garden > grazing land, but Freundlich P buffering capacity (PBC) followed the order cropland > grazing land > home garden > woodlot. Langmuir bonding energy (bL) and Freundlich phosphate sorption affinity (1/n) were in the order of home garden > woodlot > grazing land > cropland. The Qmax was positively correlated (p < 0.05) with clay, Kf, PBC, the oxalate and dithionates extractable Al, Fe, and Mn, but it negatively correlated (p < 0.05) with soil pH, SOC, AP and bL. Conclusion. Generally, the effect of P sorption of the smallholding home garden was slightly different from eucalyptus woodlot and grazing lands but considerably different from cropland. The high P sorption capacity in cropland was attributed to the high amorphous and crystalline Fe/Al oxides/hydroxides, low SOC, and low soil pH. Hence, combinations of P managements are required for increasing P availability in the smallholding land uses.

Background: Soil fertility decline in agricultural land is due to intensive cropping system, shortening of the fallow period, reduced manure application, extensive use of crop residues as fuelor fodder and removal of ground cover. This study investigated the effect of biochar (BC), lime and farmyard manure (FYM) on growth, yield and grain nutrient of wheat on two cropland sites in southern Ethiopia. Result: The effect of site was significant (P < 0.05) for most parameters investigated, indicating the influence of soil type. The effects of BC, lime, and FYM were significant (p ≤ 0.001) on straw yield, grain yield, and total biomass. However, BC (5 tha -1 ) produced the highest straw yield, grain yield, and total biomass. Similarly, BC and lime significantly (P < 0.001) affected plant height, and tiller numbers and productivity. BC (5 tha -1 ) gave the highest plant height, total tillers, and productive tillers, maximum number of seeds per spike, while FYM (10 tha -1 ) produced the highest spike length. Biochar significantly (P < 0.05) increased the concentrations of P and K in wheat grain. The highest effect on grain Ca concentration was from the application of lime while the highest on grain N concentration was from FYM (10 tha -1 ). Conclusion: The effect from BC was attributed to improvements in soil pH, CEC, nutrient availability and water retention. Thus BC has a good potential as a soil amendment for smallholder farm crop production.