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- ItemClean weeding showed positive effects on earthworm communities following six years of minimum tillage in a maize field in northern Zimbabwe(Taylor & Francis Group - Informa UK Limited, 2022-03-22) Mashavakure, Nilton; Gutukunhuwa, Bliss; Mashingaidze, Arnold B.; Gandiwa, EdsonEarthworms are a major component of soil fauna communities with positive effects on soil chemical, biological and physical processes. A study was carried out to investigate the medium-term effects of cultural practices on earthworm communities in an agricultural field. Data were collected in the 2018/2019 cropping season from a six-year-old experiment with tillage system, fertiliser application rate and weeding intensity as the main, sub- and sub-subplots, respectively. Lumbricus (34.4%) and Diplocardia (38.3%) were the dominant genera, while endogeic earthworms (48.4%) dominated the community structure among other earthworm functional groups. Clean weeded plots under the basin planting system had higher Lumbricus abundance (quadruple), genus richness (76.4%) and Shannon diversity index (56.0%) than all other treatments. Inorganic fertiliser application in the conventional tillage system reduced Eisenia abundance and genus evenness by 100.0% and 73.3%, respectively. These results suggest that in minimum tillage systems, frequent hand weeding confers positive effects on earthworms including increased abundance. In conventional tillage systems, application of high doses of inorganic fertiliser is detrimental to earthworm communities. Further studies need to focus on identifying the most sustainable and cost-effective hand weeding frequency for enhanced earthworm diversity and increased crop productivity.
- ItemField investigation of topsoil moisture and temperature as drivers for decomposition or germination of sclerotia (Sclerotinia sclerotiorum) under winter-killed cover crops(Taylor & Francis Group - Informa UK Limited, 2021-12-26) Euteneuer, P.; Wagentristl, H.; Pauer, M.; Keimerl, M.; Schachinger, C.; Bodner, G.; Piepho, H-P; Steinkellner, S.Cover cropping provides versatile benefits for sustainable agriculture, but many cover crops are potential host plants for pathogens such as Sclerotinia sclerotiorum (Lib.) de Bary. Therefore, 14 cover crops were investigated for their interaction with sclerotia, topsoil moisture and temperature in two consecutive field trials in East Austria. In July, after the cover crops were sown, sclerotia were inoculated at 3 cm soil depth in two mesh tubes per plot with 1×1 mm and 3×10 mm mesh size and remained until March. Cover crops did not affect decay of sclerotia, but sclerotia declined faster in 3×10 mm mesh compared to 1×1 mm (75.7 and 54.7%; respectively). Degree days reached the required 500 °C for apothecia development in September in both years, but only in year 1 was topsoil moisture sufficient for apothecia development. Nonmetric dimensional scaling revealed that, among others, topsoil temperature in March was significant for sclerotia germination in spring and was independent of plant biomass. There are indications that Poaceae such as sorghum × Sudan grass and Sudan grass can stimulate early germination under cover crops, causing vulnerability of sclerotia to degradation. This could reduce the pathogen pressure for the subsequent irrigated cash crops.
- ItemForage legumes exhibit a differential potential to compete against maize and weeds and to restore soil fertility in a maize-forage legume intercrop(Taylor & Francis Group - Informa UK Limited, 2021-11-16) Kutamahufa, Marilyn; Matare, Lincoln; Soropoa, Gabriel; Mashavakure, Nilton; Svotwa, Ezekia; Mashingaidze, Arnold B.Integrating forage legumes with maize has the potential to restore soil fertility and increase grain yield among smallholder farming systems. A study was conducted over two cropping seasons to determine the effect of intercropping maize with forage legumes on soil fertility restoration, weed biomass and maize yield. Treatments involved: four cropping systems (sole maize, maize-velvet bean, maize-silverleaf, maize-cowpeas) and four fertiliser regimes (no fertiliser, 150 kg ha−1 of compound D fertiliser (7% N: 14% P2O5: 7% K2O) + 150 kg ha−1 ammonium nitrate (34.5% N), 100 kg ha−1 single super phosphate (SSP, 17.5% P2O5) and 200 kg ha−1 SSP). Maize-velvet bean intercropping reduced weed biomass by 80% relative to sole maize and maize-silverleaf intercropping. Maize-cowpea and maize-velvet bean intercropping reduced maize grain yield by 25.9% and 64.7%, respectively, compared to sole maize and maize-silverleaf intercropping. In 2017/2018, maize-silverleaf intercropping increased resin-extractable P2O5 by 60.1% compared to other cropping systems while the three fertiliser treatments increased the levels of this nutrient by 41.9–100%. The results of this study show that intercropping maize with silverleaf has the potential to restore soil fertility and control weeds, without reducing maize grain yield.