3 results
Continuous cropping legumes in semi-arid Southern Africa: Legume productivity and soil health implications
- Arun D. Jani, Timothy N. Motis, Joy M. Longfellow, Brandon J. Lingbeek, Christopher J. D’Aiuto
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- Journal:
- Experimental Agriculture / Volume 58 / 2022
- Published online by Cambridge University Press:
- 22 April 2022, e15
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Legume agronomic research in Southern Africa has often focused on integrating legumes into smallholder cereal cropping systems, but there is limited information available on the feasibility and soil health implications of continuous cropping legumes in the region. Continuous legumes may be suitable in areas with large livestock populations where a premium is placed on high-quality forage, or where efforts are underway to reclaim degraded cropland. Our objectives in this study were to (i) evaluate the performance of diverse legumes under continuous cropping and conservation tillage management with no fertility inputs and (ii) assess the response of soil health parameters to continuous legumes in a semi-arid environment. A 4-year study was conducted in Limpopo, South Africa beginning in the 2011–2012 growing season in which 10 legume and fallow treatments were imposed in the same plots for 4 growing seasons. All legumes responded negatively in varying degrees to continuous cropping in terms of biomass and nutrient accumulation. Lablab (Lablab purpureus L.) was the top-performing legume in the study and accumulated 4.5–13 Mg ha−1 of biomass and 153–345, 11–34, and 75–286 kg ha−1 of N, P, and K, respectively. Lablab often outperformed natural fallow, while other legumes generally performed as well as or inferior to natural fallow, depending on species and growing season. Cowpea (Vigna unguiculata Walp) was especially incompatible with continuous cropping and averaged less than 252 kg ha−1 and 2.1 Mg ha−1 of grain and biomass, respectively, from 2012–2013 to 2014–2015. Continuous cropping did not lead to sustained improvements in soil health. By 2014–2015, soil organic matter for all treatments had either declined or resembled baseline values. Rates of potentially mineralizable N in cowpea, lablab, vining mucuna (Mucuna pruriens var. Utilis), natural fallow, and bare ground plots fell by 70–96% during the study. There was also evidence for lower recovery of leached K by legumes compared to natural fallow species. In conclusion, legumes, such as lablab, should be considered as continuous forages on marginal land in areas where high-quality forage is in demand, but continuous cropping legumes without fertility inputs are not an effective strategy for improving soil health on degraded cropland in this semi-arid region of Southern Africa. Future research efforts may focus on the grazing strategies and baling frequencies required to optimize annual biomass accumulation of continuous lablab to meet livestock demand and support smallholder livelihoods.
Low-cost seed storage technologies for development impact of small-scale seed saving entities in tropical climates
- Patrick Trail, Timothy Motis, Stacy Swartz, Abram Bicksler
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- Journal:
- Experimental Agriculture / Volume 57 / Issue 5-6 / December 2021
- Published online by Cambridge University Press:
- 07 February 2022, pp. 324-337
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Seeds can deteriorate rapidly under high heat and humidity, making it challenging and potentially costly to store orthodox seeds effectively in the tropics, thereby affecting agriculture development. This work explores the effectiveness of novel, low-cost technologies for storing seeds in warm, humid, resource-constrained environments, focusing on maintaining the viability of seeds already dry prior to storage. Seeds of okra (Abelmoschus esculentus (L.) Moench), sorghum (Sorghum bicolor (L.) Moench), and velvet bean (Mucuna pruriens (L.) DC) were kept for 12 months under roofed, outdoor screened porches. Seed moisture content prior to treatment was 6, 9, and 12% for okra, sorghum, and velvet bean, respectively. Treatments, replicated four times at each of two locations (USA [Florida] and Thailand), were technology suites involving vacuum drawn on glass jars with a modified bicycle pump, vacuum drawn on polyethylene bags with an electric vacuum sealing machine, desiccant (calcium oxide powder or zeolite Drying Beads® at a 2:1 ratio, by weight, of seeds to desiccant) in glass jars, and nontreated seeds in paper bags. Ambient temperature and humidity were variable and high, reaching over 35 °C and 83%, respectively, at both locations. Under these conditions, okra and sorghum germination percentages (across locations) without treatment declined from over 90% initially to 30 and 0%, respectively, by month 12. Both vacuum treatments and calcium oxide maintained high germination of okra (≈ 80%) and velvet bean seeds (nearly 100%) across locations. Glass, however, was superior to polyethylene in maintaining vacuum and stabilizing the moisture content of okra and sorghum seeds. Only zeolite reduced seed moisture below initial values, drying seeds to ultradry levels of <5%. With zeolite, sorghum germination stayed near 70% over time, while okra and velvet bean germination fell to <40 and <20%, respectively, by month 12, suggesting that, with the beads kept with dry seeds in storage rather than removing the beads after reaching a target level of seed moisture, the 2:1 ratio of seed-to-bead weight was too high for seeds that are sensitive to ultralow moisture. Findings have practical implications for inexpensive household- or community-level seed storage to deliver development impact.
Season-Long Interference of Yellow Nutsedge (Cyperus esculentus) with Polyethylene-Mulched Bell Pepper (Capsicum annuum)
- Timothy N. Motis, Salvadore J. Locascio, James P. Gilreath, William M. Stall
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- Journal:
- Weed Technology / Volume 17 / Issue 3 / September 2003
- Published online by Cambridge University Press:
- 20 January 2017, pp. 543-549
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Yellow nutsedge, a weed commonly present in Florida vegetable fields, may substantially reduce crop yields when not controlled. Soil fumigation with methyl bromide effectively controls nutsedges, but methyl bromide is being phased out of production and use in the United States. Therefore, nutsedge management in bell pepper is a cause for concern. An experiment was conducted during four seasons (spring and fall of 1999 and 2000) to determine the tolerance of bell pepper grown at two in-row spacings (23 and 31 cm) to interference resulting from planted yellow nutsedge tuber densities (0 to 120 tubers/m2). Relative to yields with no nutsedge, pepper fruit yields in each season were reduced 10% with fewer than 5 planted tubers/m2. Yield losses increased more rapidly with an increase in initial nutsedge density from 0 to 30 than from 30 to 120 tubers/m2. With 30 nutsedge tubers/m2, large fruit yield was reduced 54 to 74% compared to that with no nutsedge. Nutsedge shoots overtopped the pepper plants as early as 6 wk after treatment when, with 15 planted tubers/m2, nutsedge interference reduced pepper plant biomass by 10 to 47%. In the absence of methyl bromide, weed control strategies with high efficacy against yellow nutsedge will be needed for bell pepper production.
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