Department of Soil and Geological Sciences

Permanent URI for this communityhttp://10.10.97.169:4000/handle/123456789/23

Browse

Now showing 1 - 5 of 5

Evaluation of the impact of alternative wheat residue and water management on soil properties and soybean yield in a wheat-soybean double-crop system, Eastern Arkansas
(University of Arkansas, 2008-12) Amuri, Nyambilila
Long-term agricultural sustainability requires evaluation of agricultural management practices that may improve and sustain soil quality and crop productivity over time. The objective of this study was to determine the 6-yr effects of tillage [conventional (CT) and no-tillage (NT)], wheat residue burning (bum and no bum), residue level (low and high), and 3-yr irrigation (irrigated and dry-land condition), on soybean [Glycine max (L.) Men-.] yield, soil physical and chemical properties in the top 10 cm, and weed population diversity in a wheat [Triticum aestivum (L.)]-soybean double-crop production system. A field experiment was conducted from fall 2001 through fall 2007 in the Mississippi River Delta region of eastern Arkansas on a Calloway silt loam (fine silty, mixed, active, thermic Glossaquic Fraglossudalf). Soil bulk density increased at a greater magnitude under NT (1.22 to 1.35 g cm'3) than CT (1.19 to 1.26 g cm*3) during the first 3 years, but declined at a similar rate in both tillage treatments after the third year. Irrigation increased soil pH (0.2 pH unit yr*1), Mehlich-3 extractable soil Mg (55.1 kg Mg ha*1 yr*1), and total C contents (0.11 kg C m*2 yr*1) compared to dry-land condition which had no pH change, but had less increase of extractable Mg (36.6 kg Mg ha*1 yr*1), and total C content (0.04 kg C m*2 yr*1). Soil organic matter (SOM) increased over time in all treatment combinations. Total C (TC) increased at a greater rate in the no bum (0.077 kg C m*2 yr*1) and high-residue-level (0.073 kg C m*2 yr*1) than in the bum (0.051 kg C m*2 yr*1) and low-residue-level (0.054 kg C m*2 yr*1) treatments. The total weed species density was greater under CT (513 plants m*2) than under NT (340 plants m*2) early in the soybean growing season in 2006, but did not differ between tillage treatments in 2007. Perennial weed density was greaterunder bum (99 plants m"2) than no bum (59 plants m’2) in 2006, and in 2007, was greater under NT than CT but unaffected by bum. Retaining crop residues and herbicide application reduced the density of all weed species, grass, and broadleaf weed species. Tillage, burning, and residue level generally did not affect soil penetration resistance in the top 0.20-m in 2003 and in 2006, but soil cone index (CI) was consistently lower under bum than no bum at all depth below 0.20 m. The CI at the 0.05-m depth increased by 35% after 4 years compared to after 1 year of NT soybean. Soybean yield differed over years of the trials. Soybean yield declined during the first 3 years, but increased over the subsequent 3 years in all treatment combinations. Economic analysis showed that management practices with NT will likely be more profitable than the traditional CT practice even when the fertilizer and diesel costs continue to increase. Therefore, NT and non-burning with any residue level have great potential to improve soil quality, reduce weed pressure in the soybean growing season, and maintain profitability in the wheat soybean double-crop production system.
Minjingu phosphate rock solubilization and potential for use of klebsiella variicola-mde4 and klebsiella variicola-mdg1 as biofertilizer for maize production
(Journal of Central European Agriculture, 2022) Kwaslema, Damiano; Tindwa, Hamisi; Amuri, Nyambilila
Limited solubility of the Tanzania’s Minjingu phosphate rock (MPR) in non-acidic soil conditions has held back its potential for widespread use in agricultural production. This study was designed to isolate, characterize and test phosphate-solubilizing bacteria for their potential to increase solubility of MPR and enhance maize plant growth under field conditions. Ten out of 19 isolates showing greatest phosphate solubilization indices on a Pikovskaya agar medium were further characterized for other plant-growth promoting traits including production of IAA, siderophores and ammonia. Two of them, namely isolates-MdE4 and MdG1 substantially outperformed other isolates in phosphate solubilization and production of IAA, ammonia and siderophores. The two isolates molecularly identified as Klebsiella variicola-MdE4 and K. variicola-MdG1 produced up 701, 699 and 750, 680 µg/ml of soluble phosphate from tricalcium phosphate and hard Minjungu rock phosphate, respectively. Additionally, Biorock P- a biofertilizer formulation containing MdE4 and MdG1 co-cultured in a molasses-based modified broth medium retained most of the phosphate solubilizing potential and other plant-growth promoting traits of MdE4 and MdG1. Co-application of MdE1 and MdG1-containing “bio-rock P” and inorganic phosphate at 20 kg P/ha resulted in higher maize grain yield than that of positive control (40 kg P/ha) under field conditions. The two isolates- Klebsiella variicola-MdE4 and K. variicola-MdG1 have the potential for use in a biofertilizer formulation for commercial field applications.
Modeling potential rain-fed maize productivity and yield gaps in the Wami river sub-basin, Tanzania
(Taylor And Francis Journals, 2015) Mourice, Sixbert Kajumula; Tumbo, Siza Donald; Amuri, Nyambilila; Rweyemamu, Cornell Lawrence
The cause for low maize yields in rain-fed production systems is usually associated with water stress due to perceived suboptimal seasonal precipitation. A modeling study using Agricultural Model Intercomparison and Improvement Project modeling framework was conducted to determine the magnitude of rain-fed potential yield and yield gap of maize in the Wami River sub-basin, Tanzania. Primary and secondary data on soils, weather, management, and crop yields and cultivars were used. Data matrix search technique was used to calibrate CERES-Maize Crop System model against reported yield for each of 168 farms involved in this study. Then the individual farms’ simulated yields, actual reported yields, and the resultant yield gaps were aggregated into ward-level averages. Model calibration was robust as there was a very close agreement between reported and simulated yield (R2 = 0.9). Actual yields reported from farm survey ranged from 50 kg ha−1 to 3600 kg ha−1 with an average of 860 kg ha−1 . Simulated rain-fed potential yield was between 2073 kg ha−1 and 5443 kg ha−1 and a mean of 4033 kg ha−1 . It is apparent therefore that there exists a wide maize yield gap of 79% with current management under rain-fed conditions. This suggests that there is a large scope of improving maize yields under rain-fed conditions. Narrowing the yield gaps would require an intensive soil fertility improvement in the study area.
Soil property and soybean yield trends in response to alternative wheat residue management practices in a wheat-soybean, double-crop production system in eastern Arkansas
(Electronic Journal of Integrative Biosciences, 2008) Amuri, Nyambilila; Brye, Kristofor R; Gbur, Edward E; Popp, Jennie; Chen, Pengyin
Growing concerns over the long-term sustainability of agricultural systems require investigation of agricultural management practices that may improve and sustain soil quality and crop productivity over time. Over 20% of the soybean [Glycine max (L.) Merr.] area in the highly productive Mississippi River Delta region of the mid southern United States is in a double-crop rotation with wheat [Triticum aestivum (L.)]. Currently, much of the resulting wheat residue is managed by burning followed by conventional tillage, but this combination may not be environmentally sustainable. Therefore, the objective of this study was to determine the long term effects of tillage [conventional (CT) and no-tillage (NT)], wheat-residue burning (burn and no burn), wheat-residue level (low and high, achieved with differential N fertilization), and irrigation (irrigated and dry-land) on soybean yield, net economic returns, and soil properties in the top 10 cm of a wheat -soybean, double-crop production system. A field experiment was conducted from 2001 through 2007 in the Mississippi River Delta region of eastern Arkansas on a Calloway silt loam (fine silty, mixed, active, thermic Glossaquic Fraglossudalf). Soil bulk density increased in both CT and NT during the first three years, but at a greater rate under NT (0.12 g cm-3 yr-1) than CT (0.08 g cm-3 yr-1), followed by a decline at a similar rate in both tillage treatments. Soil pH and Mehlich-3 extractable soil Ca and Mg contents increased, while electrical conductivity decreased linearly over time when all treatments were combined. Soil organic matter (SOM) increased over time in all treatment combinations. Total C (TC) increased at a greater rate in the no burn (0.08 kg C m-2 yr-1) and high-residue level (0.07 kg C m-2 yr-1) than in the burn (0.05 kg C m-2 yr-1) and low-residue-level (0.05 kg C m-2 yr-1) treatments. Extractable soil P content declined linearly over time at greater rate under NT (3.3 kg P ha-1 yr-1) and high-residue-level (3.4 kg P ha-1 yr-1) than under CT (2.6 kg P ha-1 yr-1) and low-residue-level (2.4 kg P ha-1 yr-1) treatments. Soybean yield declined at a similar rate in the first three years, but increased at a similar rate over the subsequent three years in all tillage-treatment combinations. Increasing SOM and TC over time indicated that the silt-loam soils of the Mississippi River Delta region have the potential to accumulate C in the top 10 cm at increasing rates beyond six years from initial conversion to alternative residue management practices. Implementation of the appropriate residue management practices has the potential to improve soil quality and maintain long-term productivity of silt-loam soils in the Mississippi River Delta region of the mid-southern United States.
Weed populations as affected by residue management practices in a wheat-soybean double-crop production system
(Cambridge University Press, 2010) Amuri, Nyambilila; Brye, Kristofor R; Gbur, dward E; Dick, Oliver; Jason, kelly
Management practices and cropping systems that serve as integrated weed management practices, and at the same time can contribute to improved soil quality, will be important for the sustainability of agricultural production systems. The objective of this study was to assess weed species population density under contrasting tillage (conventional tillage [CT] and no tillage [NT]), residue burning (burn and no burn), and residue level (low and high) treatments after 5 and 6 yr of consistent management in a wheat-soybean double-crop production system. A field experiment was conducted from fall 2001 to fall 2007 in the Mississippi River Delta region of eastern Arkansas on a Calloway silt-loam. Weed assessments were conducted twice during the soybean growing season, before (early season) and after herbicide application (late season) in 2006 and 2007. Total weed density was greater under CT (513 plants m ) than under NT (340 plants m ) early in the growing season in 2006, but was greater under NT than CT late in the season in 2007, suggesting that the effectiveness of glyphosate on total weeds differs between CT and NT. Averaged across residue levels, grass species density was greatest in the NT-burn (68 to 167 plants m ) combination and lowest in the NT-no-burn (41 to 63 plants m ) early in the growing season in both years. Broadleaf density was greater early (200 to 349 plants m ) than late (18 to 20 plants m ) in the growing season under both CT and NT in 2006, but in 2007 broadleaf density did not differ by tillage treatment between seasons. Perennial weed density was greater in the burn (99 plants m ) than in the no-burn (59 plants m ) treatment in 2006. No tillage, no burning, and a high residue level appeared to contribute to the suppression of most weed species without reducing herbicide efficiency. Nomenclature: Soybean, Glycine max Merr.; wheat, Triticum aestivum

Browse

Browsing Department of Soil and Geological Sciences by Author "Amuri, Nyambilila"