Effect of Long-Term Tillage Practices on Soil Physico-Chemical Properties and Weed Population Dynamics in a 36-Year Old Experiment
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Changes to tillage practices can influence soil physico-chemical properties and weed population dynamics. Experiments were conducted in 2016 and 2017 in a 36-year long tillage experiment at Texas A&M University, College Station, TX to study the impact of tillage regimes on soil physio-chemical properties and weed population dynamics in monoculture grain sorghum (Sorghum bicolor), and weed dynamics alone in monoculture soybean (Glycine max). The tillage systems studied include conventional-tillage (CT) and no-tillage (NT). Results showed that tillage did not affect soil bulk density, total porosity, air filled porosity, water-filled pore space and volumetric water content. However, water holding capacity, soil organic carbon, and cumulative carbon mineralization were 25, 43, and 16% greater in the NT system, compared to CT, at the 0 to 5 cm soil depth. Conversely, cumulative water infiltration and CO2 emission were greater in the CT system (23.66 cm hr^–1 and 7.28 g m^–2) than NT (3.98 cm hr^–1 and 5.19 g m^–2) in 5 and 24 hrs study. The long-term tillage regimes also influenced weed population dynamics and seedling emergence in grain sorghum and soybean. Greater densities of Johnsongrass (Sorghum halepense), prostrate spurge (Chamaesyce humistrata), tall waterhemp (Amaranthus tuberculatus), henbit (Lamium amplexicaule) and shepherd’s purse (Capsella bursa-pastoris) were recorded in the NT system, compared to the CT system in both crops. The long-term NT system was characterized by greater weed diversity (Shannon-Wiener’s index, H = 0.8) and species richness (S = 6.2) compared to CT (H = 0.6; S = 4.2) in sorghum; however, no differences were found in weed species diversity in soybean. Moreover, a greater proportion of the viable seedbank was located in the top 5 cm soil depth in the NT system (24 to 96% depending on the weed species) compared to the CT system (22 to 61%). Overall, results illustrated that long-term NT practices can provide environmental benefits and are more sustainable than CT. However, growers shifting to NT practices should consider potential changes to weed population dynamics and adjust the management programs accordingly.
Govindasamy, Prabhu (2018). Effect of Long-Term Tillage Practices on Soil Physico-Chemical Properties and Weed Population Dynamics in a 36-Year Old Experiment. Doctoral dissertation, Texas A & M University. Available electronically from