Thesis (M.S.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 3, 2008) Includes bibliographical references.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 63-64). Also available on the Internet.

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on October 2, 2009). Thesis advisors: Dr. J. W. Van Sambeek, Dr. Frieda Eivazi. Includes bibliographical references.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 63-64). Also available on the Internet.

Limited photosynthetically active radiation (PAR) can reduce interseeded cover crop growth in corn (Zea mays L.). Two experiments in North Dakota evaluated the effect that hybrid relative maturity (RM), row width, and cover crop planting date have on cereal rye (Secale cereale L.) and winter camelina [Camelina sativa (L.) Crantz.] establishment when interseeded into 80 and 89 RM hybrids at V7 and R4 growth stages in 56- and 76 cm corn row widths. Cover crop biomass was typically less than 100 kg ha-1. In the following spring larger amounts of PAR beneath the 80 RM hybrid increased cover crop biomass by 20.8 kg ha-1. Cover crop biomass tended to be greater in the 76 cm row width but was not significantly different from the 56 cm width. Cover crops decreased residual soil nitrate by 6.0 kg ha-1 in the fall and by 15.6 kg ha-1 in the spring.

No description available.

Thesis (M.Sc. (Agronomy )) --University of Limpopo, 2007 / Intercropping is the growing of two or more crops simultaneously on the same field, and it is a common traditional practice among resource-poor farmers throughout the Limpopo Province of South Africa. Field studies were conducted at two locations in the province namely, the University of Limpopo experimental farm at Syferkuil, and a farmer’s field at Dalmada during the 2002/2003 growing season, to determine patterns of nodulation in cowpea and lablab varieties under sole culture and in an intercropping system with maize, variety SNK2147 and also to assess biomass accumulation and grain yielding abilities of the component crops in the system. The experiments were established as a randomized complete block design with three replications at each location. Treatments examined were sole maize, two cowpea cultivars: Bechuana white and Glenda; two lablab cultivars, Rongai and Common. The legumes were intercropped alternately within 90 cm inter-row spacing of maize, thus creating a distance of 45 cm between the maize and the legume rows. Cropping system had no effect on cowpea grain yield at Syferkuil, but at Dalmada cowpea yield was reduced. Maize grain yield was significantly affected by the cropping system at both Syferkuil and Dalmada. At both locations, the yields of all the intercropped maize were lower than those of the sole crop maize. The dry matter production of different cropping systems was generally similar during the different sampling dates. / the National Research Foundation,and the Gauteng Department of Agriculture Conservation and Environment

Thesis (MSc. Agriculture (Agronomy)) -- University of Limpopo, 2013 / Maize (Zea mays L.) is the third most important cereal crop after wheat and rice in the world. Maize/legume intercropping system has become one of the solutions for food security among small scale maize producers due to unaffordability of chemical nitrogenous fertilizers and limited access to arable land. A study was conducted to determine the effect of maize/dry bean and maize/lablab intercropping on maize grain yield and soil fertility status. A field experiment was conducted during 2010/2011 and 2011/2012 growing seasons at the University of Limpopo experimental farm. Treatments included sole maize (ZM 521, an improved open pollinated variety, ex- CIMMYT), sole lablab (Rongai, indeterminate cultivar), sole dry bean (DBS 360, indeterminate Type II cultivar), maize/dry bean and maize/lablab intercrops arranged in randomized complete block design with five replications. Phosphorus (P) was applied on sole and intercropped maize at the rate of 30 kg P/ha in the form of superphosphate (10.5%P) at planting and 40 kg N/ha of nitrogen (N) was applied in the form of Limestone Ammonium Nitrate (LAN) (28%N) on both sole and intercropped maize four weeks after plant emergence. For maize and dry bean, grain yield, yield components and biomass were determined. Only biomass yield was measured for lablab. Soil samples were collected for soil analysis at the beginning and the end of the experiment The results showed that maize/lablab intercropping yielded significantly (P<0.05) lowered maize grain (1259.3 kg/ha) than sole maize and maize/dry bean intercropping which yielded maize grain of 2093.7 kg/ha and 2156.3 kg/ha, respectively. Sole dry bean yielded significantly (P <0.05) higher dry bean grain (1778.5 kg/ha) than intercropped dry bean (691.8 kg/ha). Rongai was only flowering by the time maize and dry bean matured hence only maize yield is reported for the Maize/lablab intercrop. Maize/dry bean intercropping was advantageous to sole cropping with a Land Equivalent Ratio (LER) of 1.42. The partial Land Equivalent Ratio (PLER) for maize in maize/lablab intercropping was 0.60. Dry bean was outcompeted by maize as calculated aggressivity value was positive at +0.64.The highest monetary value was achieved in sole dry bean and the lowest monetary value was found in intercrop dry bean. Soil TN, P, K, Ca, Mg and Na were reduced by both sole cropping and intercropping systems. Intercropping with lablab is likely to significantly lower maize yield under dryland conditions. Key words: dry bean, grain yield, Intercropping, lablab, maize, smallholder, soil fertility.

Thesis (Ph.D. (Plant Production)) -- University of Limpopo, 2022 / Sustainable food production has been a major challenge in the era of climate change and a growing population in the twenty-first century. However, climate change scenarios such as extreme temperatures and fluctuations in annual precipitation continue to pose a great threat to agricultural production systems. On the other hand, anthropogenic activities such as conventional farming continue to contribute to climate change through the emission of greenhouse gases while not sustaining agricultural production. The Food and Agriculture Organization of the United Nations (FAO-UN) developed the concept of Climate-Smart Agricultural (CSA) production with the idea of securing food in the face of global change. No-tillage and intercropping systems are among the traditional practices that are advocated as components of climate-smart traditional practices, especially in the semi-arid regions of Africa like the Limpopo Province. Producing sorghum and cowpeas using CSA practices such as intercropping under no-tillage is envisaged to increase productivity and soil fertility under Limpopo Province's dryland conditions. However, there is still limited information on how grain sorghum-cowpea intercrop will respond in terms of growth, physiological productivity, and carbon dioxide emissions in the system, especially under no-tillage and different growing conditions. Furthermore, more field data is required for predictions of future scenarios using simulating crop models such as the Agricultural Production system sImulator (APSIM). Hence, a no-till Randomized Complete Block Design (RCBD) in a 2 x 4 x 2 factorial arrangement was conducted at two locations (Syferkuil and Ofcolaco) in the Limpopo Province during the 2018/19 and 2020/21 cropping seasons to generate data on sorghum and cowpea growth, physiology, productivity as well as carbon dynamics under planted and simulated intercropping system. Leaf gaseous exchange and leaf area index (LAI) were measured on fully developed grain sorghum and cowpea leaves in both the binary and sole cultures of sorghum and cowpea. The CO2 measurements were taken from each plot using a GMP343 CO2 probe along with an MI70 data logger. Aboveground biomass was collected for each crop from two plants at vegetative, flowering, physiological and harvest maturity and oven-dried at 65 oC for 48 hours. In the 2020/21 cropping season, cowpea at Ofcolaco failed to produce grain. Hence, only the grain yield of the 2018/19 cropping season from Ofcolaco is presented in this thesis. Grains collected for each crop from a 2.7m2 area were taken to the laboratory to determine grain yield and yield components. Harvest index (HI) and land equivalent ratio (LER) for each crop were also determined. In the laboratory, the total nitrogen (%) and natural abundance of 15N (δ15N‰) were determined using an isotope ratio mass spectrometer with an N analyzer. Growth (biomass) and yield (grain) data obtained from APSIM were compared with data collected from a two-year field experiment at Syferkuil. Multi-variate analysis of variance (ANOVA) model to fit each response variable using the Statistical Analysis System (21 SAS version 9.4). Mean separation was done where the means were different using the least significant difference (LSD) at probability levels of p ≤ 0.05. Intercropping system and the density of the companion crop cowpea had a significant (p ≤ 0.05) effect on the physiological responses of sorghum and cowpea, cowpea yield and yield components at the two experimental sites across seasons. However, grain yield and yield components of sorghum were not affected by intercropping or the density of cowpea. Only cultivars of sorghum were significantly different for grain yield and yield components. At Syferkuil, Enforcer produced the highest grain yield of 4338 kg ha-1 in 2018/19, while NS5511 accumulated the highest grain yield of 2120 kg ha-1 during the 2020/21 cropping seasons. At Ofcolaco, Enforcer and Avenger were observed to be relatively high-yielding cultivars with a mean grain yield of 2625 kg ha- 1 and 1191 kg ha-1 during the 2018/19 and 2020/21 cropping seasons, respectively. In the 2018/19 and 2020/21 cropping seasons, respectively, cowpea accumulated about 93% and 77% more grain yield in sole compared to binary culture. At Ofcolaco, about 96% more grain yield was obtained in sole compared to binary cultures during the 2018/19 cropping season. Furthermore, cowpea accumulated over 55% and 49% of grain yield when grown at high compared to low population density at Syferkuil and Ofcolaco, respectively. The investigation on the impact of the intercropping system on CO2 emissions and soil carbon stocks revealed that in 2018/19 at Syferkuil and 2020/21 at Ofcolaco, intercropping systems emitted 11% and 19% less CO2 respectively than the sole cropping systems. In both diverse agro-ecological sites, low cowpea density consistently resulted in higher CO2 emissions than high density. The sorghum-cowpea intercropping system significantly influenced the biological nitrogen fixation of cowpea. Intercropping was found to improve the biological nitrogen fixation of cowpea if a density of 74074 plants ha-1 is used. The APSIM model was able to capture the dynamics of biomass and grain yields in the sole and intercropping system under different densities of cowpea. The findings of this study revealed some useful insights. Firstly, biomass accumulation depended on the cultivar in intercrop as well as the density of cowpea. Secondly, cowpea at a density of 74074 plants ha1 was found to be a good crop to intercrop with grain sorghum as it did not show any significant variation in terms of grain yield and yield components of sorghum. The sorghum cultivar, Enforcer and NS5511 were the best performing cultivars in terms of grain yields at Syferkuil and Ofcolaco. Thirdly, the intercropping system under high cowpea density reduced CO2 emission rates while improving soil nitrogen (N) and carbon stocks. Based on the results of this study, grain sorghum-cowpea intercrop can be adopted as a component of a climate-smart practice to improve crop growth, physiology, as well as productivity compared to sole cropping. However, the grain sorghum cultivar and the density of cowpea should be taken into consideration as they affect the productivity of the two crops. The two seasons data generated from this study was useful in simulating the productivity of intercropping practice using APSIM. However, more field and weather data is required to run long-term simulations on intercropping as a component of the climate-smart method using crop modelling techniques. / National Research Foundation (NRF), Departments of Science and Innovation (DSI) and VLIR-IUC (Belgium)

Intercropping is defined as a management approach where two or more crops are planted on the same forested site simultaneously. The advantages of applying this concept on young pine plantations in the south can increase site utilization, reduce weed competition, provide annual or semi-annual revenues early in the timber rotation, ameliorate the soil, and diversify production. Research was initiated to determine the feasibility of using various plants as intercrops on pine plantations in Virginia and North Carolina. Regional crops were categorized into four groups based on management intensity, end use, and crop value. These crop groups included: 1. Field Crops: Corn, Sorghum, Cotton, Small Grains, 2. High Value Crops: Tobacco, Peanuts, Snap Beans, Tomatoes, Cucurbits, 3. Forage Crops: Grasses and Legumes, 4. Biomass Crops: sycamore, Sweet Gum, European Black Alder, Cottonwood. The ecological and management characteristics of these crops were examined to determine their compatibility with pine plantation management. In every case, three significant constraints were noted; intercropping on plantations reduced the number of trees carried to maturity by 50 to 60 percent; intercrop production was highly sensitive to row spacings and required seedling row widths of 4 to 8 m; and great emphasis was placed on site preparation, with per hectare costs increasing by approximately 250 percent. Investment analysis of several hypothetical intercrop scenarios suggested that forest intercropping can be financially rewarding under a variety of crop combinations. Intensively managed intercrops provided substantially greater returns than a conventional plantation investment. A field crop-pine combination was the most attractive intercrop scenario for large scale plantation intercropping, due to consistently high profit margins, low total investment costs, and fewer marketing constraints. Vegetable-pine combinations were typically high cost alternatives which generated equally attractive net revenues. However, the high costs and intensive management requirements restricted the introduction of vegetable crops to small plantation acreages where adequate attention would be available. Forage and biomass intercrops were relatively inferior investments relative to the more intensive vegetable and field crop combinations. Wide intercrop spacings dramatically increased average DBH of simulated pine stands configured for intercrop management, resulting in greater sawlog and veneer size log production and lower yields of pulpwood sized timber. Although the difference in net revenue from the pine component marginally favored the intercropped plantation, the difference in product mix suggests that companies or individuals interested in diverse timber products may wish to consider plantation intercropping as one means of diversifying plantation timber yields. Further study is suggested to quantify the biological effects of forest intercropping on component crops, with emphasis on intensively managed crops. Practical application is restricted to fertile, highly productive plantation sites capable of supporting both agricultural and forest crops. / Ph. D.