ABSTRACT
In response to rapid population growth and the need for more agricultural products, many countries in the world are engaged in an intensive irrigation development. As these efforts, in many cases, are following injudicious uses of water, environmental challenges such as widespread of soil salinity are emerging in many instances. The Nigerian northern nigeria system, where this study was conducted, exhibits this problem. Research addressing these challenges, using locally accessible material such as rice straw compost and mulch are rarely available. Thus, this study was conducted at Zaria, Kaduna state with the objective of evaluating effects of rice straw compost application rate (0, 2, 4 and 6 ton/ha) and mulch thickness (0cm/ha, 5cm/ha, 10cm/ha, and 15 cm/ha) on yield and yield quality of irrigated tomato. The experiment was conducted in factorial experiment arranged in a Randomized complete block design with three replications. The post-harvest soil result indicated that Mg, Om%, CEC, Ec (ds)/m, Na, and Available (Av .P) ppm were significantly (p<0.01) affected by the interaction effects of rice straw compost application rates and mulch thicknesses. However, pH, TN%, OC%, and Ca are significantly (p<0.01) affected by the main effects of rice straw compost application rate. The interaction effects of the treatments, on the other hand, did not affect days to 50% flowering and days to 50% maturity. These variables, however, were significantly (p<0.01) affected by the rice straw compost application rates. The growth variables were also not significantly affected by the interaction effects of rice straw compost and mulch thickness. Except single fruit weight per plant and fruit shape index, all yield and yield component variables were significantly affected by the interaction effects of mulch thickness and rice straw compost application rate. Yield obtained from the treatment combination of 6ton/ha rice straw compost rate and 10cm mulch thickness was agronomically and economically remunerative by 15.56% for farmers. Nevertheless, because of the slow releases of nutrient from rice straw compost and organic mulch, long term effect of this rate needs further investigation.
CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Soil fertility is fundamental in determining the productivity of all farming systems and is most commonly defined in terms of the ability of a soil to supply nutrients to crop (Wild, 1993). Salinization and low soil nutrient content are some of the major problem that hampers crop production on smallholder farmers field. About 20% of the world cultivated land and 50% of cropland generally affected by salinity (Lakhdar et al., 2009). Salt affected soil in Nigeria is reported to cover over 11 million hectares of unproductive naturally salt affected wastelands (Tadele, 1993). The natural affected areas are normally found in the arid and semi arid lowlands and in northern nigeria and other areas that are characterized by higher evapotranspiration rates in relation to precipitation (PGRC, 1996).With the expansion of irrigated agriculture, man’s activities contributing to the build-up and spread of salinity.
The social cost of salinization is not easy to quantify as it causes occupational and geographic shifting of the farm population and reduction in aggregate national income and expenditure. These events can have social and economic repercussions on the country as a whole.
Maintenance of high crop yields under intensive cultivation is possible only with external fertilizer inputs (organic and in organic sources fertilizer). Although inorganic fertilizers application is the quickest and easiest way of increasing yield per unit area, the problems associated with inorganic nutrient supplementation, if not judiciously handled, it can causes pollution of ground water and does not improve soil structure and may early contribute to greenhouse gases (GHG) (Gordon et al., 1993).
Tomato (Solanum lycopersicumL.) is one of the most widely cultivated crops in the world. It is an important source of vitamin A (30%), vitamin C (38%), calcium (2%), iron (3%) and is an important cash crop for smallholders and medium-scale commercial farmers (Naika S et al., 2005). Tomato is widely cultivated in Nigeria: both under rain fed and irrigated systems.
Despite this economically important position there is growing concern that the region is affected by land degradation mainly due to the rapidly growing population and lack of proper soil fertility management practices (Jansen et al., 2007). Many reports indicate that, in Nigeria, and in the northern nigeria areas, the low productivity of vegetables including tomato, is attributed to low or depleting soil fertility, poor agronomic practices such as imbalanced fertilization (Fekadu et al., 2006). Additionally increasing ground water table, in some part, and soil salinity and sodicity become some of the major concerns. Large sodium content exist in the lower part of the Northern nigeria where soil pH present from 8.5 to 10.0 (OWRDB, 2009). Although salinity and sodicity are common phenomena for arid and semiarid regions of the world, salt-affected soils have been recorded in all climatic regions and in a wide range of altitudes in Nigeria (Tena, 2002; and Paulos et al., 2002)
Salt affects tomato plant growth mainly through toxicity from excessive uptake of salt substances such as sodium, reduced water uptake, known as water stress and reduction in uptake of essential nutrients particularly potassium (FAO, 2005). Similar problems were observed in the northern nigeria including Dugda Bora and generally, the production is low in terms of quantity and quality. This affects not only the productivity but also the quality and associated consumer’s preferences (Aleligne et al., 1994).
Proper soil fertility management practices may alleviate the declining soil fertility and improve crop tolerance to salinity and thus enhances crop yield and quality (Ouedrago et al., 2001). Complementary use of organic with inorganic fertilizer is widely known to be reliable fertility management strategy in many countries of the world (Lombion et al., 1991). This emphasized that high and sustained crop yields can be obtained with judicious and balanced NPK fertilizer application combined with organic fertilizer (Makinde et al., 2001). Rice straw compost addition increased water content at both field capacity and permanent wilting point, increased shoot and root growth under stressed condition and also can decreases the effects of salinity by increase soil water availability and nutrient uptake by plants (Nguye et al., 2013). Organic mulches containing sawdust, dry grass (lawn clippings), maize cobs, rice and wheat straw have been very effective for vegetable growth and yield through improving water content of the soil, heat energy and add some of the organic nitrogen and other mineral to improve nutrient status of the soil.
Surface mulching has shown to reduce evaporation and decrease salinity hazards to improve crop production (Yang et al., 2006). This means also combined application of organic fertilizer and mulching will address the twin problems of tomato production in the northern nigeria system
Zaria is the area where many smallholder farmers are producing vegetable crop by irrigation. Among these vegetables tomato, one of the most widely grown, is severely affected by salinity (personal communication). The major salts at Meki-Ogolcha area are chloride, sulphate, bicarbonate, and to some extent, the availability of nitrate salts of Na, Mg and K and cation exchange capacity of soil varied within and between profiles (Kefyalew et al., 2008). Vegetable growers in the northern nigeria (CRV) areas are trying to amend the soil fertility of irrigated lands through application of inorganic fertilizers, crop residues and animal wastes, and use crop rotations. But, this is not common for all farmers. They use variable rate of fertilizers and crop and soil specific recommendations are rare to find (Edossa et al., 2013)
Even though several attempts like integrated soil fertility management (use of fertilizer, organic inputs, and improved crop varieties have been made to manage soil salinity (Vanlauwe et al., 2010), there are limited empirical evidences whether or not the farmers used technology such as mulch and rice straw compost to decrease the effects of salinity on vegetable product and the impact of these practices on quality and productivity. With this premises this study was initiated with the following objectives.
1.2 PROBLEM STATEMENT
Tomato (Solanum lycopersicumL.) is one of the most widely cultivated crops in the world. Many reports indicate that, in Nigeria, and in the northern nigeria areas, the low productivity of vegetables including tomato, is attributed to low or depleting soil fertility, poor agronomic practices such as imbalanced fertilization (Fekadu et al., 2006). Additionally increasing ground water table, in some part, and soil salinity and sodicity become some of the major concerns. Large sodium content exist in the lower part of the Northern nigeria where soil pH present from 8.5 to 10.0 (OWRDB, 2009). Although salinity and sodicity are common phenomena for arid and semiarid regions of the world, salt-affected soils have been recorded in all climatic regions and in a wide range of altitudes in Nigeria (Tena, 2002; and Paulos et al., 2002)
1.3 General objectives
- To evaluate tomato yield and quality under salt affected soil by using different rates of rice straw compost and mulch thickness
Specific objectives
- To evaluate effects of rice straw compost and mulch on soil physicochemical properties under salt affected soil
- To evaluate effect of mulch and rice straw compost on tomato yield and quality under salt affected soil
- To identify optimum rice straw compost application rate and mulch thickness for tomato production in the
- To identify the best economically suitable rice straw compost rate and much thickness for tomato production.
1.4 SCOPE AND LIMITATION OF THE STUDY
This study which is titled the assessment of soil nutrient content and growth of tomato as affected by rice straw compost treatment is aimed at determining the effect of the application of rice straw compost on soil nutrient and growth of tomatoes. The study will be carried out in zaria city, kaduna state, Nigeria. The researcher was limited by time an
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