The study attempts to develop a quick and a simple phosphorus (P) testing method to get the idea about the P level in the soil for farmers so that they may be able to decide the amount of phosphorus fertilizer for their cultivation. Four new phosphorus extraction methods were used which are Mogen's method, distilled water method, basify distilled water method and acetic acid method. Extracted phosphorus was measured by Murphy and Riley colorimetric method and correlated each method with the Olsen method because Olsen method has grown in stature and reputation over the years as the best and cheapest method suitable for mild acidic to base soils. The significant correlations (r 2 ) of Mogen method, distilled water extraction method, basify distilled water extraction method and acetic acid extraction methods with Olsen method were 0.734, 0.585, 0.654, and 0.854 respectively. The acetic acid phosphorus extraction method which has the best correlation with the Olsen method was further simplified and its significant correlation with the Olsen method was 0.855. Simplified acetic acid method was the best simple P extraction method in the field level test and the extracted P can be measured using the newly introduced color chart in this study. Subsequently a field soil testing kit was developed based on the results for the farmers to test the soil phosphorus content by themselves before the cultivation and decide on phosphorus fertilizer application.
Vegetable cultivation in Sri Lanka is an intensive and highly commercialized system. Since, vegetables are heavy nutrient feeders that produce high biomass within a short period, management of fertilizers and amendments are critical for sustainable production. The objective of this study was to assess the fertilizer and amendment usage by intensively vegetable cultivating farmers in Sri Lanka and identify the relationship between farmer practices and their productivity using a questionnaire survey. Study was conducted with randomly selected 100 farmers each from Nuwara Eliya (NE) and Marassana (M) regions. Data were obtained on relative use of inorganic fertilizers, organic amendments and liming materials, with respect to the current recommendations. The vegetable cultivating systems of the two regions were identified as vegetable-potato-vegetable and vegetablepaddy-vegetable for NE and M, respectively. The productivity of crops cultivated in NE was higher than that of M. While about 25% and 67% of farmers in NE and M, respectively, used synthetic fertilizers more than the recommended level, about 66% (NE) to 99% (M) farmers used less than 50% of the recommended organic manure quantities for their vegetable crops. We attributed these differences to other crops included in the rotation, availability and high cost of organic fertilizers, and the value of crops, in addition to the cash subsidy given for synthetic fertilizers. Productivity of fields in M, where moisture stresses are more common, appeared not related to the relative quantity of fertilizer or amendments used. However, the productivity was maximized around 70-90% of recommended level of fertilizers among farmers in NE. We concluded that site-specific fertilizer best management practices need to be introduced to intensively cultivating farmers in Sri Lanka, in order to increase and sustain productivity.
Morphological variation of 16 rice accessions representing both traditional and improved varieties was assessed using 12 vegetative traits as described in International Rice Research Institute descriptor for rice, in sand medium using a Complete Randomized Design. The single linkage clustering, morphological dendrogram, multivariate analysis of variance and the Principal Components Analysis were performed to assess the traits. According to the cluster analysis, accessions 2840 and 10617 were the most closely associated among the varieties. Based on the variations associated with morphologically important vegetative traits, all the rice accessions were classified into three major groups as two traditional and one new improved variety groups. Existence of such clusters was validated by the Wilks' lambda statistics. The first four principle components explained over 80% of the total variation associated with the varieties. Among them the first two principle component cumulatively explained 54.46% of the total variation. Rice accessions 8920 and 2835 representing Bg360 and Bg 450, respectively showed the highest principle component 1scores. Traditional rice varieties showed the comparatively higher scores in both principle components 1 and 2 than newly improved varieties. This study indicated that measured vegetative agro-morphological traits were helpful for preliminary characterization of varieties and also they can be used as a broad-spectrum approach to assess morphological diversity among morphologically distinguishable rice accessions.
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