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Open Access
Potassium utilization in cassava (Manihot utilissina pohl) as influenced by neem cake - urea blend
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 1985) Manorama Thampatti, K C; KAU; Padmaja, P
Potassium utilization in cassava (manihot utilissima pohl.) as influenced by neem cake – urea blend. An investigation was carried out at the College of Horticulture, Vellanikkara, during the year 1983-84, which include a soil column study to understand the dynamics of NH4+- N and K+ ions when applied as urea or urea-neem cake blend either alone or along with muriate of potash. The columns were filled with soil collected from the field surface upto 60 cm depth. Each 15 cm was taken as a separate layer maintaining the same bulk density as observed in the field. Fertilizer treatments comprising, no fertilizer, urea or urea-neem cake blend to supply 100 ppm N and muriate of potash to supply 100 ppm K either alone or in combination were applied to the surface 15 cm soil and mixed thoroughly. The study indicated that under natural conditions NH4+ - N was concentrated more in the lower layers of soil beyond the root zone of cassava whereas potassium was concentrated more in the surface layers of 0-30 cm depth. Application of muriate of potash either alone or in combination with urea-neem cake blend increased potassium in the surface layer within eight hours after fertilizer application. When untreated urea granules were applied along with potassic fertilizer, a major part NH4+ - N was found either concentrated in lower layers, or nitrified and lost. But when urea-neem cake blend was applied along with potassic fertilizer a major part of nitrogen was retained as NH4+ - N in the surface layers upto two weeks and later it moved downwards. There was a drastic reduction of NH4+ - N status in the surface layers upto 45 cm after one week in untreated urea, whereas urea-neem cake blend maintained much of NH4+ - N in the surface 30 cm upto three weeks. Application of muriate of potash maintained highest potassium status followed by urea-neem cake blend along with muriate of potash. The maximum leaching loss of potassium was observed from untreated urea when applied along with muriate of potash. The loss was reduced considerably when potassic fertilizer was applied along with urea-neem cake blend. A field experiment was conducted as a continuation of the study carried out at the College of Agriculture, Vellayani, when urea-neem cake blend at 5:3 ratio increased nitrogen availability, nitrogen uptake and yield. But it had an adverse effect on potassium utilization of the crop resulting in poor quality tubers and the yield increase observed was not significant. The present experiment was planned to tide over this difficulty either by changing the time of application or increasing the rate of potassic fertilizer. Results of the experiment clearly showed that urea-neem cake blend increased nitrogen use efficiency of cassava as evident in higher soil available nitrogen and higher nitrogen uptake by the crop. When muriate of potash was applied one month after application of urea-neem cake blend, the uptake of potassium was not reduced considerably in the initial stages and at the same time uptake was comparatively higher at the sixth month and harvest stages. Potassium at 75 kg K2O ha-1 increased uptake of all nutrients and also produced maximum tuber yield of 21.39 tonnes ha-1, whereas application of potassium one month after application of urea-neem cake blend recorded 19.76 tonnes ha-1 of tuber yield which was on par with the former treatment. Potassium uptake at all major growth stages were significantly correlated with plant dry weight and tuber yield. Maximum benefit per rupee invested was obtained when the rate of potassium was raised from 50 kg K2O ha-1 to 75 kg K2O ha-1 along with 50 kg N as urea-neem cake blend. Changing the time of application of potassic fertilizers to one month and three months after planting also increased the benefit obtained. Both three treatments were on par with each other and significantly superior to others.
Open Access
Suitability of rockphosphate for direct application in acid rice soils of Kerala
(Department of Soil Science and Agricultural Chemistry, College of Horticulture, Vellanikkara, 1985) Regi, P Mathews; KAU; Jose, A I
An incubation study and a potculture experiment were conducted to assess the suitability of Rajastan rockphosphate (RRP) supplied from Rajastan State Mineral Development Corporation, in comparison with that of Mussooria rockphosphate (MRP) supplied from pyrites phosphate and chemicals Ltd. (U. P) and superphosphate (SP) in two acid rice soils of Kerala namely laterite (Kodakara, Trichur district) and kari (karumadi, Alleppey district) soils. Transformations of P fertilizers applied at the rate of 45 and 90 kg P2O5/ha in these soils under continuous submergence were studied in the incubation experiment. Soil samples were drawn at 15 days interval for the determination of various inorganic P fractions and available P. The direct and residual effects of the two rockphosphates in comparison with the water soluble SP were studied in the potculture experiment using rice (Jaya) as the test crop. The soils and levels of P applications were the same as in the incubation study. Application of N and K was done uniformly in all the treatments. Soil and plant samples were drawn at 15 days interval for the determination of available P and the uptake of major nutrients. The residual effect of phosphatic fertilizers was assed by continuing the experiment for the second season with out the addition of P fertilizers. However, for the second season a treatment receiving P at the rate of 45 kg P2O5/ha as SP in both the season was incorporated for comparison in both the soils. Application of phosphatic fertilizers irrespective of their water solubility increased the various inorganic fractions and available P content of the soil. The total native inorganic P increased in the presence of added P due to the enhanced mineralization of organic P. Among the various inorganic fractions, Fe-P was the dominant form accounting for 41 to 44 per cent of the total inorganic P. Second most abundant fraction was A1-P. The contents of reductant soluble-P, occluded-P and Ca-P were relatively less and that of saloid-P was negligible. The three sources of P did not differ significantly in increasing the various inorganic fractions of the soil except that of saloid-P. The contents of A1-P, Fe-P, reductant soluble-P and occluded-P were more in laterite soil compared to kari soil, while saloid-P and Ca-P were high in kari soil. Prediction equations were worked out to establish various inorganic P fractions and available-P at different periods of incubation. The peak values of saloid-P were observed during the seventh fortnight. Saloid-P was found to be positively correlated with Fe-P (r = 0.77*2*), AI-P (r = 0.73*1*) and Ca-P (r = 0.27*8*) and negatively correlated with reductant soluble-P (r = -0.249*) and occluded-P (r = -0.31*9*). Concentrations of AI-P and Fe-P were maximum during the twelfth period of sampling and they were negatively correlated with reductant soluble-P occluded-P. Highest values of reductant soluble-P and occluded-P were observed during the first period of incubation and the concentration of Ca-P was minimum in the twelfth fortnight. Forms and levels of applied P had little effect on increasing the available P content of the soil. The contribution of various inorganic fractions to available P was different. Direct and indirect effects of various inorganic P fractions on available P from RRP, MRP and SP were brought out by the path analysis. Saloid-P, Fe-P, AI-P and Ca-P were positively correlated with available P (Bray 1 and 2) and reductant soluble-P and occluded-P were negatively correlated. The extent of contribution of various inorganic fractions to available P was the same in all the three sources of P added to the soil. Application of SP at the rate of 90 kg P2O5/ha twice in two equal doses during the first and ninety-first day of incubation did not increase conspicuously the inorganic fractions and available P content of the soil compared to the initial application of the same quantity of P as SP and rockphosphate. In the potculture experiment in general, application of P fertilizers had resulted in a better utilization of major nutrients by the rice plant and this effect was more pronounced in kari soil during the first crop season. However, in the second crop season, the effect of P fertilizers on uptake of nutrients was pronounced in both the soils. During the first crop season, in the absence of added P, the uptake of nutrients and yield of straw and grain were more in laterite soil compared to kari soil while in the presence of added P, uptake of nutrients and yield were higher in kari soil. However, in the second crop season, both in the presence and absence of added P, the uptake of nutrients and yield were more in laterite soil. Uptake of N and K by the straw during the first crop season was significantly higher in treatments receiving SP compared to other treatments receiving rockphosphates though the uptake of P by the straw did not vary significantly with the variations in the source of P. However, in the second crop season, uptake of N, P and K by the straw was significantly higher in treatments receiving SP. Increasing the level of application of P from 45 to 90 kg P2O5/ha increased the uptake of N and K significantly while uptake of P by the straw and straw yield did not increase significantly with increasing the level of application. But in the second crop season, the uptake of N, P and K by the straw and straw yield increased markedly with increasing the level of application. Uptake of N and P by the grain of the first crop did not increase significantly over control in laterite soil, while that of K showed significant increase over control in both the soils. However, in the second crop, uptake of N, P and K by the grain increased conspicuously in both these soils. In the first crop season, total uptake of K was significantly higher over control in both the soils, while that of N and P was higher only in kari soil. But the total uptake of N, P and K increased over control in both the soils in the second crop season. In general, application of SP was found to be superior to the application of rockphosphates with respect of the uptake of N, P and K grain and their total uptake by rice plant in both the seasons of crop growth. The yield of grain by the application of phosphatic fertilizers showed significant increase over control only in kari soil during the first crop season. In the second crop season, both the soils were found to be responsive to the application of P fertilizers with respect to the increase in the yield of grain. In the treatments receiving rockphosphates as a source of P, the yield of grain was 93.18 and 92.67 per cent of that obtained in treatments receiving SP during the first crop and second crop seasons respectively. In both the seasons of crop growth, available P in the soil was significantly higher in treatments receiving SP than that in treatments receiving rockphosphates. Increasing the level of application of P from 45 to 90 kg P2O5/ha increased the available P content of the soil to the extent of 11.97 and 17.43 per cent over the lower level during the first and second crop seasons respectively. Application of SP at the rate of 90 kg P2O5/ha applied twice in two equal doses separately for the first crop and second crop seasons increased the uptake of nutrients, yield of grain and straw and available P content of the soil compared to the application of the same total quantity of P initially for the first crop only as SP and rockphosphate.
Open Access
RoIe of boron in plant nutrition in Kerala in relation to its content in soils
(Department of Soil Science and Agricultural Chemistry,College of Agriculture, Vellayani, 1985) Suresh, P R; KAU; Abdul Hameed
An investigation was carried out to elucidate the role of boron in crop nutrition especially in crops of relevance to Kerala in relation to its content in major upland soil types« 'Tho work included in tho present study is on four main soil types of Trivandrum district namely forest red 1aterite and sandy soil in relation to two major crops namely coconut and banana grown on them A critical evaluation of soil in relation to plant boron status of the four soil types revealed that forest soils are having the highest content of available boron as compared to other soil typos# The indicator plants in the study also showed a close parallel relationship to soil boron status. Between the indicator plant species chosen in all for soil types tho boron content of banana leaves were invariably higher than that of coconut leaves The soil factors like N, P, K and Ca content of tho soil did not show any correlation with the available boron of tho soil# Tho organic matter content of tho soil showed a significant positive correlationship with tho available boron status in sandy soils. This suggests tho need for using organic manures in such soils whore boron deficiency occurs The hot water attractable boron shows a positive and significant correlation with the loaf boron status of both coconut and banana
Open Access
Nitrogen fixation by cowpea as influenced by the stage of growth and duration of crop
(Department of Soil Science and Agricultural Chemistry,College of Agriculture, Vellayani, 1985) Indira, M; KAU; Alice Abraham
A field experiment was conducted in the College of Agriculture, Vellayani to study the quantity of nitrogen fixed by, cowpea at various stages of growth and also to find its residual effect on a succeeding crop of fodder maize The field trial was laid out as RBD and split plot design with six replications. The study revealed that the growth characters and dry matter production of cowpea increased with increasing age of the crop. The content of plant nitrogen decreased with advancing age eventhough the total uptake of nitrogen » showed an increasing trend from 579 g/plot at the maximum flowering to 657 g/plot at the maturity stage of the crop. Uptake of other nutrients like phosphorus, potassium, calcium and magnesium also showed an increasing trend towards the maturity stage of the crop. The ratios of these nutrients with respect to nitrogen narrowed with increase in the duration of the crop. The total residual nitrogen status of the soil recorded a gradual increase towards the maturity stage of the crop. The value increased from 0.0514 per cent at the maximum flowering stage to 0.0553 per cent at the maturity stage. The available nitrogen status of the soil at various stages of growth of cowpea remained unaltered. The quantity of nitrogen fixed by cowpea was found to be 23, 67 and 112 kg/ha at the maximum flowering, mid pod filling and maturity stages of the crop respectively. All these indicate that nitrogen fixing processes in cowpea are active during its entire growth period gaining pace after the maximum flowering stage of the plant. The highest residual effect due to nitrogen fixed by oowpea was obtained from plots where It was grown upto maturity as seen from the general growth characters and fodder production of maize. Uptake of the nutrients such as nitrogen, phosphorus and potassium in fodder maize was also highest in plots where oowpea was grown upto maturity.The nitrogen made available from the decomposition of plant residues at any of the three stages of cowpea was always lower than that obtained from the addition of 30 kg M/ha.The highest fodder yield (20.7 t/ha) was obtained from plots which. received an additional amount of 60 kg U/ha over and above the residual nitrogen in.the soil where cowpea was grown upto maturity. The residual effect of nitrogen in the soil where cowpea was grown .upto maturity was reckoned on equivalent to the effect of 60 kg N/ha. The study has brought out the fact that maximum nitrogen gain through fixation, by growing legume crops can be achieved only if the plant is allowed to complete its full growth period.
Open Access
Studies on the root activity pattern of black pepper employing radiotracer technique
(Department of soil science and agricultural chemistry, College of Horticulture, Vellanikkara, 1985) Jayasree, Sankar S; KAU; Wahid, P A
An investigation on the root activity pattern of black pepper vine and allied aspects was conducted employing phosphorus-32. The results indicated that the active root zone of black pepper vine trailed either on erythrina or on teak pole is in a soil column of 30 cm radius around the vine. It is suggested that fertilizer application to pepper vines may be done in a semicircle of 30 cm radius facing the vine for the most effective utilization of the added nutrients. Growing the vine in association with erythrina as support was found to reduce the uptake of 32p by at least 20 per cent as compared to that grown on teak pole. The active root system of erythrina was found to be more extensive than the vine reaching upto 60 cm from the pepper plant. The absorption of 32p by the climbing roots of the vine was found to be insignificant. A method of leaf sampling for 32p assay in black pepper vine as well as a method of soil injection of 32p solution into root zone of crop plants was developed. Annual exhaust of nutrients by way of harvest of 1.284 kg dry pepper was found to be 38.5g N, 36.7 g K, 14.9 g Ca, 13.7 g Mg, 2.2 g P, 1.37 g S, 218 mg Fe, 155 mg Mn, 28 mg Zn and 47 mg of Cu. From the defoliation of erythrina, an annual recycling of 0.7 kg dry matter containing 25.7 g N, 0.94 g P, 6.5 g K, 20 g each of Ca and Mg, 0.8 g S, 131.4 mg Fe, 1008 mg Mn, 13 mg Zn and 14.2 mg Cu may be expected.
Open Access
Physico-chemical characterisation of red soils in different regions of Kerala
(Department of soil science and agricultural chemistry, College of Horticulture, Vellanikkara, 1985) Betty, Bastin; KAU; Venugopal, V K
In the present study an attempt has been made to evaluate the morphological, physical and chemical characteristics of red soils occurring in different regions of Kerala. Six soil series representing red soils identified by the soil survey unit of the department of Agriculture, Kerala state were selected for the investigation. The series identified were Vellayani, Cherniyoor, Bharanikkavu, Beypore, Chirakkal and Kunhimangalam located in Trivandrum, Quilon, Calicut and Cannanore districts. Profile pits were dug at these different locations and examined for their morphological features. Soil samples representing the different horizons were collected for laboratory studies. The physico-chemical characteristics of the soils and chemical composition of clays of the profile samples were investigated with a view to study the interrelationship between the various properties and to relate these characteristics to the genesis of these soils. Surface samples collected from different locations under each series were also analysed for available nutrients. The morphological features of the soil profiles revealed prominent red hues with increase in redness with depth. All the soil profiles were well drained, with ill defined horizons, exhibited good structural development and were devoid of coarse fragments. The soils were all sandy in nature, with the fine sand fraction predominating. Clay illuviation was observed in all the profiles. In respect of available water content appreciable variation was not observed between soil series. The highest available water content was recorded in Kunhimangalam series while beypore series had the lowest. All soils were acidic with very low electrical conductivity. The organic carbon, nitrogen and C/N ratios were low and showed little variation between soil series. Silica recorded very high values for all the soils while total Fe2 O3 and AI2 O3 did not reveal much variations between soil series. The total reserves of CaO, MgO, K2 O and P2 O5 were very low and is mainly a reflection of minerology of sand fraction which was dominated by quartz. In respect of total micronutrients iron and manganese recorded high values while Zinc and copper were low and did not reveal much variations between the different soils. Iron, Zinc and copper showed positive relationship with finer fraction while in the case of manganese, the relationship holds good in the case of fine sand fraction only. The e. c. e. c. values obtained were very low and less than the c. e. c. values determined by neutral N NH4 OAc method. Effective c. e. c. showed positive significant relationship with organic matter. The content of exchangeable bases were in the order Ca Mg Na K. Exchangeable hydrogen was more than exchangeable aluminium. Cherniyoor series recorded the highest percentage base saturation while the lowest value was obtained for Kunhimangalam series. The dithionite extractable iron was the predominant iron fraction in all the soils and based on the ‘degree of freeness of iron’ Kunhimangalam series was the oldest in respect of age followed by Chirakkal, Cherniyoor, Vellayani, Beypore and Bharanikkavu. The Ammonium oxalate extractable iron and iron oxide ratio, recorded very low values for all the soil series. The available nutrients of the surface samples showed high levels of phosphorus in all the soils. Nitrogen was low to medium in Vellayani, Cherniyoor and Beypore while it was medium in Bharanikkavu, Chirakkal and Kunhimangalam series. In the case of available potassium loe to medium levels were observed in Chirakkal, Bharanikkavu, Beypore and Cherniyoor series while Kunhimangalam and Vellayani series showed low levels of available potassium. The phosphorus fixing capacity for all the series was high. The DTPA extractable iron and manganese were more than adequate in the surface horizons of all the series. Zinc was deficient to adequate in Vellayani, Bharanikkavu and Kunhimangalam series and marginal to adequate in Cherniyoor, Beypore and Chirakkal series. Copper was deficient to adequate to Vellayani, Cherniyoor and Kunhimangalam series, while adequate levels were observed in Bharanikkavu, Beypore and Chirakkal series. Silica formed the predominant element of the clay fraction. The Si O2/AI2 O3, Si O2/Fe2 O3 and Si O2/R2 O3 ratios recorded for all the soils were higher than the values reported for typical laterite soils.

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