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Impact of Management on Soil Fertility and Rice Yields in Smallholder Farms in Tanzania
Sutton, Claire L

2015, Master of Science, Ohio State University, Environmental Science.
As a response to agronomic constraints present in a particular irrigation scheme of Tanzania, an experiment was funded by USAID as part of the Feed the Future Initiative to evaluate two sustainable agriculture systems and the suitability of Moshi, Tanzania for Conservation Agriculture (CA) and the System of Rice Intensification (SRI). The CA system involves reduced tillage, residue retention, and crop rotation on a field growing rice (Oryza sativa L.) and maize (Zea mays L.). The System of Rice Intensification requires fewer seeds, planting of younger seedlings, reducing plant density of transplants, while reducing the amount of water used throughout the season.

The objectives of this specific study are to: 1) Classify the soil of the region based on profile evaluation and soil analysis, 2) Use the Universal Soil Loss Equation to calculate the average annual soil loss of the Lower Moshi Irrigation Scheme, 3) Evaluate the impact of different management techniques on key soil properties for continuous rice and maize-rice rotation, and 4) Assess the impacts of CA and SRI on agronomic productivity. The two fields used in this study are located in the Lower Moshi Irrigation Scheme and are smallholder farms, 0.3 ha in size.
The soil was classified as a Eutric Cambisol and a Eutrustept. The average soil loss from sheet and rill erosion was calculated using ArcGIS, and Universal Soil Loss Equation to be 4.91 Mg ha-1.
The soils of the study sites had never been tested in a quantitative manner. The soil was recently tested as part of this project for many properties critical to determining soil structure, fertility, and classification. Carbon and nitrogen concentrations were highest in the top 20 cm of the soil, and the pH and electrical conductivity were within ideal ranges for crop production. Nitrogen and carbon concentrations did not vary significantly between an N, P, K fertilization and urea application at either field site. The field that cultivated rice continuously had higher carbon stocks, at an average of 20.15 Mg C ha-1, than the maize-rice rotation field which averaged 13.51 Mg C ha-1. Total nitrogen concentrations were higher in the continuous rice field, averaging 1.4 g N kg-1 and the maize-rice rotation averaging 0.75 g N kg-1.

The results of this study found improved crop yields compared to national averages and demonstrated that any chemical inputs or residue can improve crop yields. The average crop yields of this study were significantly higher in the continuous rice field that produced IR64 variety of rice, averaging 9.53 Mg ha-1. The maize-rice rotation more than doubled the national average rice yield when a local variety of SARO 5 was planted and averaged 5.26 Mg ha-1. The level of water had a much smaller impact on crop yields than rice variety or nutrients applied. The water level used in the SRI treatments was 4 cm and not continuously flooded which saved nearly twice the amount of water compared with the conventional management of a continuously flooded water level of 7 cm.
Rattan Lal (Advisor)
Brian Slater (Committee Member)
Steve Culman (Committee Member)
123 p.

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Sutton, C. (2015). Impact of Management on Soil Fertility and Rice Yields in Smallholder Farms in Tanzania. (Electronic Thesis or Dissertation). Retrieved from https://etd.ohiolink.edu/

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Sutton, Claire. "Impact of Management on Soil Fertility and Rice Yields in Smallholder Farms in Tanzania." Electronic Thesis or Dissertation. Ohio State University, 2015. OhioLINK Electronic Theses and Dissertations Center. 24 Sep 2017.

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Sutton, Claire "Impact of Management on Soil Fertility and Rice Yields in Smallholder Farms in Tanzania." Electronic Thesis or Dissertation. Ohio State University, 2015. https://etd.ohiolink.edu/

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