The Cation Exchange Capacity, pH of Soil in Mwogo Marshland, and the Rice Plantation in Huye District -Rwanda
Abstract
Agriculture is a major component of Rwanda’snational economy. In 2017, agriculture contributed 33% to the country’s GDP. About 66.46 % of population, of which 50.9 % are women, depends either directly or indirectly on agriculture for living. The average arable surface area available is about 0.60 ha per household use. This causes overexploitation of available land which is often accompanied by agricultural malpractices with disastrous consequences on land resources and on environment in general. Given the limited availability of arable land for agriculture and the constantly growing food requirements of the population, ensuring food security poses a major challenge. This present study aimed at investigating the cation exchange capacity and pH of soil of Mwogo Marshaland in order to resolving the problem of soil fertility of Mwogo marshland by looking the method for increasing its fertility and then the problem of low rice production. By using soil Auger, samples were taken randomly in the field where each sample of soil was used in laboratory to determine both pH and Cation Exchange Capacity, in each blocks namely Block du Nord and Block du Sud. During this study the laboratory results and laboratory analysis has shown that marshland soil is very acidity with pHkcl is 4.37, Ph water with a weak cation exchange capacity. These findings support the previous studies showing that the soils with those properties need particular management; like liming, addition of organic matter, and so on, in order to adjust its chemical properties.
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Introduction
Soil property influencing soil structure stability, nutrient availability, soil pH and the soil’sreaction to fertilizers and other ameliorants (Hazleton and Murphy 2007). The Cation Exchange capacity of soils varies according the type of soil, soil pH and amount of organic matter, for example the pure sand soil is contains low cation exchange capacity, less than 2 meq/100 g. The research of Mckinze stated that soils with large quantities of negative charge are more fertile because they retain more cations (McKenzie et al. 2004) however; productive crops and pastures can be grown on low cation exchange capacity soils. The main ions associated with cation exchange capacity in soils are the exchangeable cations calcium (Ca2+), magnesium (Mg2+), sodium (Na+) and potassium (K+) (Rayment and Higginson 1992). However, assoils become more acidic these cations are replaced by H+, Al3+ and Mn2+, which affect soil fertility and some plants do notable to grow in that situation (McKenzie et al. 2004). As a consequence, Brady (2012) argued that acidic soils, range of hydrologic and climatic condition are affecting growth and production of rice (Brady, 2012).
In small and very densely populated country Rwanda, the average arable surface area available is about 0.60 ha per household lead people to overexploit land activities, convert pastures and woodlots into cropland and cultivate in malpractice which fragmented, fragile, steep-sloping of areas and cause also soil infertility ( Imerzoukene and Van Ranst, 2001). Other characteristics of the subsistence agriculture in Rwanda are the lack of individual and regional specialization, a weak integration between agriculture and the economic markets, and an important dependence on the climatic conditions which resulting a serious decrease of the physical and chemical soil fertility and affect crop yields (Imerzoukene and Van Ranst, 2001).
Rice plantation has been adapted as major crop need empowerment in Rwanda in order to cop that challenge of food insecurity. In the past 10 years, the total rice production has increased by 6-fold from 11,949 tons in 2000 to 72,000 tons in 2009. Rwanda annually imports Tanzanian, Indian and Pakistan long grain rice: 57,229 MT (2012) while Rwanda produced only short grain rice (Kigori): 81,908 MT (2012) which is very low compare to the needs of population and lead the rice consumption be outstripped to the local production.
In the same case, the rice productivity of Mwogo marshland is critical due to the soil nutrient depletion which is directly linked to food insecurity of country and local community. Many factors are associated such as nitrogen, phosphorus, Insufficient mechanization of farming operations, therefore this study was focused on effect analysis of cation exchange capacity and soil ph on soil fertility of Mwogo marshland thereby the soil fertility continues to decline and this declining is showed by low production of rice. This study aims to end up by resolving the problem of soil fertility of Mwogo marshland by looking the method for increasing its fertility. The specific objectives of this study are to: Assess soil PH and cation exchange capacity of mwogo marshland, determine the effect of CEC and soil Ph of Mwogo marshland, to determine strategic way of increasing rice productivity in Mwogo marshland to measure the rate of cations exchange capacity in Mwogo marshland.
Conclusion
The study showed that soil of Mwogo marshland is acidic soil and its CEC is weak means that mwogo marshland require particular measures for increasing its productivity. Acidic conditions and its cation exchange capacity need to be ameliorated because it is not suitable for better growth of rice. Therefore, we recommend reducing soil acidity, efficient use fertilizer, improving decomposition of crop residues for Ph case while for Cation exchange capacity improvement of CEC in weathered soils by adding lime and raising the Ph is needed. The use organic matter is the most effective way of improving the CEC in this marshland.