1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Nitrogen nutrition and rhizobial inoculation on soybean(Department of Agronomy, College of Horticulture, Vellanikkara, 1978) Geethakrishnan Nair, P; Vikraman Nair, RAn experiment was conducted at the Research Station and Instructional Farm, Mannuthy during 1976 on the nitrogen nutrition and rhisobial inoculation on soybean ( Glycene max (L.) Marrill). The investigation was undertaken to assess the nitrogen requirement of the crop under inoculated and uninoculated conditions. Also the study was aimed to arrive at the fertiliser equivalent of rhisobial inoculation. The experiment was laid out in factorial in randomized block with 12 treatments and 4 replications. The study revealed that nitrogen fixed symbiotically, was adequate for the crop. Application of nitrogen depressed symbiotic nitrogen fixation and with increasing levels of nitrogen, there was depression in symbiotic nitrogen fixation. The study also revealed that introduced strain of Rhizobium japonicum was less effective in nitrogen fixation on soybean than the strains already present in the soil. Application of nitrogen didi not influence the stover yield. Inoculation of an ineffective strain tended to depress the stover yield. Application of nitrogen increased the plant height in the early stages when symbiotic nitrogen fixation could not make any substantial contribution towards nitrogen supply. Significant increase is test weight with increasing levels of nitrogen indicated that enhanced soil nitrogen supply was beneficial towards the later stages of crop growth. The quality of nitrogen fixed by the soybean plant appears to exceed the fertiliser equivalent of 250 kg N/ha applied basally.Item Moisture retention characteristic of red and forestry soil of Kerala(Department of Agronomy, College of Horticulture, Vellanikkara, 1985) Reena Mathew; Vikraman Nair, RThe investigation was undertaken in the College of Horticulture, Vellanikkara, during the period from November 1983 to September 1984. Soil samples were collected from Cannanore, Calicut and Trivandrum districts for red soil and Trivandrum, Trichur and Wynad districts for forest soil. Moisture retention studies were done at six applied pressures viz. 0.3, 1, 3, 5, 10 and 15 bars and these values were correlated with contents of textural separates and organic carbon using multiple regression analysis. The study revealed that moisture retention by 2 mm sieved soil was higher for forest soil than red soil at all the six tensions. The moisture contents on weight basis at 0.3 bar for the two soils were 24.85 and 10.45 per cent, respectively. The corresponding values at 15 bars were 18.15 and 7.21 per cent. In both the soil, the contents of fine fraction (clay and silt) showed significant positive correlation with moisture retention while the correlation with fine sand was significant and negative. Organic carbon was found to have no bearing on moisture retention as indicated by the lack of significant correlation at any of the tensions studied. The gravel fraction in the case of forest soil was found to retain moisture and the values at field capacity and permanent wilting point were 10.8 and 9.46 per cent, respectively. The moisture retention of the soil including gravel amounted to 26.90 per cent at field capacity and 20.2 per cent at permanent wilting point, on volume basis. Prediction equations were developed to estimate the moisture retention at 0.3 and 15 bars of the 2 mm sieved soil from a knowledge of the contents of organic carbon and textural constituents. In the case of forest soil, another set of prediction models was also worked out to arrive at the moisture retention including gravel at these soil moisture constants.