Browsing by Author "Kahimba, Fredrick C."

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    Nitrogen movement in coarse-textured soils and its availability to maize (Zea mays L.) plant
    (SciRes, 2013) Mthandi, John; Kahimba, Fredrick C.; Tarimo, Andrew; Banda, Salim; Lowole, Maxon
    Nitrogen (N) is the most important determinant nutrient for plant growth and crop yield. Plants lacking N show stunted growth and yellowish leaves. Plant growth and crop yield usually in- crease when N is added. However, too much N leads to weak stems in grain crops (lodging) which result into low yield. The aim of the study was to delineate changes of N concentration, its direction of movement and its pattern of dispo- sition in the soil as influenced by amount of ap- plied water and nitrogen so as to reduce N losses and maximise its absorption by maize roots.The study was conducted during irrigation seasons of 2011 and 2012 at Nkango Irrigation Scheme, Malawi. The trials consisted of factorial arrangement in a Randomised Complete Block Design (RCBD). The factors were water and N and both were at four levels. The Triscan Sensor was used to measure total N concentration at different vertical and lateral points. The study inferred that changes of N concentration, its di- rection of movement and its pattern of disposi- tion in the soil are influenced by water flux and absorption rate of plants roots due to gradient created by absorption. The study noted that when N is in low supply, its movement towards maize roots is greatly influenced by diffusion. The study concluded that to maximise N absorp- tion by maize roots, the point of N application should be at 5 cm away from the planting station to minimise N losses through drifting away from the maize rooting zone.
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    Root zone soil moisture redistribution in maize (Zea mays L.) under different water application regimes
    (SciRes, 2013) Mthandi, John; Kahimba, Fredrick C.; Tarimo, Andrew K.P.R.; Salim, Baandak A.
    Soil moisture availability to plant roots is very important for crop growth. When soil moisture is not available in the root zone, plants wilt and yield is reduced. Adequate knowledge of the distribution of soil moisture within crop’s root zone and its linkage to the amount of water ap- plied is very important as it assists in optimising the efficient use of water and reducing yield loss- es. The study aimed at evaluating the spatial redistribution of soil moisture within maize roots zone under different irrigation water application regimes. The study was conducted during two irrigatation seasons of 2012 at Nkango Irrigation Scheme, Malawi. The trials consisted of factorial arrangement in a Randomised Complete Block Design (RCBD). The factors were water and ni- trogen and both were at four levels. The Triscan Sensor was used to measure volumetric soil mo- isture contents at different vertical and lateral points. The study inferred that the degree of soil moisture loss depends on the amount of water present in the soil. The rate of soil moisture loss in 100% of full water requirement regime (100% FWRR) treatment was higher than that in 40% FWRR treatment. This was particularly noticed when maize leaves were dry. In 100% FWRR treatment, the attraction between water and the surfaces of soil particles was not tight and as such “free” water was lost through evaporation and deep percolation, while in 40% FWRR, water was strongly attracted to and held on the soil particles surfaces and as such its potential of losing water was reduced.