international fertilizer correspondent
No 4
international fertilizer correspondent No 4 |
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Oosterhuis, D.M and C.W. Bednarz: Physiological changes during the development of potassium deficiency in cotton. In: T. Ando et al. (Eds), Plant nutrition - for sustainable food production and environment, 347-351, 1997, Kluwer Academic Publishers.
Investigations were done in growth rooms and field trials to study the physiology of the onset of K deficiency in cotton. The studies show that reductions in leaf physiological processes, such as photosynthesis and translocation of assimilates, and in plant growth did not occur until the petiole K concentration fell below 0.88%. This also means that reductions in lint yield and quality should not develop until this critical petiole level is reached.
De Mesquita Filho, M.V. and M.A.P. Rincón: Potassium quantity-intensity relationships of a hydrosequence of soils from the Cerrado region of Brazil. In: T. Ando et al. (Eds) , Plant nutrition - for sustainable food production and environment, 353-354, 1997, Kluwer Academic Publishers.
The objective of this study was to apply the Q/I approach in order to evaluate the K status of representative soil samples from the Cerrado Region in Brazil. Positive correlation between the activity ratio at equilibrium and the initial exchangeable K percentage and between the buffer power and CEC of the soils were found.
Bell, R.W., D. Brady, D. Plaskett and J.F. Loneragan: Potassium deficiency diagnosis in soybean (Glycine max L. Merr.). In: T. Ando et al. (Eds), Plant nutrition - for sustainable food production and environment, 363-364, 1997, Kluwer Academic Publishers.
The study was done to determine the effect of plant age and stage of development on critical K concentration in soybean. Irrespective of reproductive development, the critical K concentration for all sampled plant parts, including leaves, petioles and stem internodes, declined steadily with plant age. The decline in critical K concentration was still evident when K concentration were expressed on a tissue water basis.
Dobermann, A., R. Nagarajan, P. Stalin, P. Mutukhrishnan and Ma. A.A. Adviento: In situ measurement of soil nutrient supply in lowland rice fields. In: T. Ando et al. (Eds), Plant nutrition - for sustainable food production and environment, 379-380, 1997, Kluwer Academic Publishers.
Ion-exchange resin capsules were used for measuring soil nutrient supply in a long-term experiment with rice. Capsules were either placed into the field or inserted into soil paste collected from the field. Soil mixing and/or intensive root-capsule contacts caused significant differences in the nutrient extraction. For assessing the indigenous soil nutrient supply in rice fields, it is recommended that the resin capsules are placed below 5 cm depth to minimise effects of top-dressed fertilizer application. To monitor changes in soil nutrient supply as affected by fertilizer application, both methods, i.e. installing the capsules into the field or using soil paste are suitable.
Liu, M., K. Tian and T. Tadano: Effects of soil salinity on the growth, nutritional status and salt-removing capacity of fodder beet. In: T. Ando et al. (Eds), Plant nutrition - for sustainable food production and environment, 421-422, 1997, Kluwer Academic Publishers.
Fodder beet which are highly tolerant to soil salinity were used to test desalinisation potential of cultivated plants. With increasing salinity, content of Na, Ca and Mg increased in beet but K content decreased. Usually, fodder beet could remove 0.35-0.9 t/ha of salt. Of course, beet tops and urine of livestock fed with beet should not be returned to the field during the desalinisation process.
Karpinets, T.W. and D.J. Greenwood: Modelling and measurement of the effects of K-fertilizer on yield, crop uptake and soil-K. In: T. Ando et al. (Eds), Plant nutrition - for sustainable food production and environment, 499-500, 1997, Kluwer Academic Publishers.
A mechanistic model is described that calculates the daily increases in plant biomass and the changes in plant K, soil exchangeable K, fixed K and K activity ratio for arable crops grown with different levels of K fertilizers. Good agreement was obtained between measured and simulated values.
Steffens, D. and K. Zarhloul: Exploitation potential for non-exchangeable potassium of Lupinus albus L. and Triticum aestivum L. In: T. Ando et al. (Eds), Plant nutrition - for sustainable food production and environ-ment, 511-512, 1997, Kluwer Academic Publishers.
Wheat and white lupin cultivated in pot experiments hardly showed a response to K indicating that both plant types have a good exploitation potential for non-exchangeable K. The exploitation potential of wheat is explained by 3 times longer roots than lupin and by a low K uptake per root length which enhances the release of non-exchangeable K. The exploitation potential of white lupin seems to be based on the excretion of citric acid.
Yamada, S., M. Osaki and T. Tadano: Effect of potassium nutrition on translocation of photosynthesized 14C and carbon-nitrogen metabolism in leaves of various crop plants. In: T. Ando et al. (Eds), Plant nutrition - for sustainable food production and environment, 889-890, 1997, Kluwer Academic Publishers.
Translocation of assimilates and C-N metabolic balance in leaves as affected by K nutrition was investigated in 2 types of plants with differences in the NK leaf ratio. Type I represent plants which show decreasing K contents with decreasing N contents like wheat or soybean. Plants of type II show constant K contents at decreasing N contents such as sunflower. Translocation of 14C assimilates and C-N metabolic balance at K deficiency was more reduced and affected in type II plants than in type I plants.
Tanaka, R.T., H.A.A. Mascarenhas, T. Muraoka and P.B. Gallo: Changes in soybean quality resulting from applica-tions of lime and potassium fertilizer. In: T. Ando et al. (Eds), Plant nutrition - for sustainable food production and environment, 943-944, 1997, Kluwer Academic Publishers.
Experiments on acid soils show that liming increased the protein content of seeds and K fertilization increased the oil content. It seems that K supply, together with liming, may have increased symbiotic activity in the "rooting zone" which helped to improve the supply of nutrients such as N. Consequently, this altered the physiological and nutritional quality of soybean seeds.