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ways satisfactory. If the greater part of K was supplied to the plant by interception and not by diffusion (see 3.2), the methods would have a greater informative value. Better results can be obtained by the determination of the K concentration in the saturated soil extract (as an approximate measure of the unstable values of the actual concentration in the soil solution) as well as with values of the K diffusion rate, the determination of which is however wearisome (van Braunschweig and Menge/ [1971)). Beckett's attempt [1971] to combine the activity ratio as an intensity parameter with the 'labile' (unstable) exchangeable potassium as a quantity parameter for the assessment of the K supply to plants suffers from the objections mentioned under 3.3.2. with regard to the activity ratio. At present two methods are known which meet the requirement that all three parameters should be taken into account the dynamic-kinetic aspect of plant nutrient supply: the exchanger method by Tepe (Tepe and Leidenjrasl [1958)) and the electroultrafiltration method by Nellleth [1972]. The exchanger method simulates the nutrient qptake by plants using a dialysing tube filled with cation and anion exchangers which for a certain period is brought into contact with the water-saturated soil. The amount of nutrients taken up by the exchanger depends on the concentration of the soil solution, the total mobilizable (exchangeable) quantity and the conditions of diffusion. This procedure therefore meets, in principle, the requirements established. The electrouItrafiltration method (EUF) uses an electric field with variations in voltage to desorb nutrient ions from a soil suspension through a semipenneable membrane. Also in this case the amounts released per unit of time (release rate) depend on the con- ' centration and the reserves available. By variations in time and voltage it has been possible to obtain three defined K fractions which give a comprehensive picture of the K supply to the plants: after a short period at low voltage a fraction corresponding to the K concentration in the soil solution, subsequently at increased voltage the fraction of exchangeable potassium, and after another interval with further increase in voltage the nonexchangeable potassium. These dynamic-kinetic methods are a promising approach which certainly will lead to consequences in practical soil testing methods, based on the knowledge that K nutrition of the plant takes place in an open and dynamic pedosystem. Barber, S. A.: Mechanism of potassium absorption by plants. In 'The Role of Potassium in Agriculture', Am. Soc. of Agron. Madison, 293-310, 1968. Beckelt, P. H. T.: Potassium potentia Is - A Review, Potash Review 5/30, 1-47 (1971). Beckett, P.: Critical cation activity ratios. Ad". Agr. 24, 379-412 (1972). mn BraufHch ..... eig, L. C. und Mengel. K.: Der Einfluss verschiedener den Kaliumzustand des Bodens charakterisierender Parameter auf den Kornertrag von Hafcr. Landw. Forsch. 26/1, Sonderheft, 65-72 (1971). Grimme, H., Nemerh, K. und von BraunJChK'eig, L. c.: Bcziehungen zwischen dem Verhalten des Kaliums im Boden und der Kaliumernlihrung der pnanze. Landw. FOl"Sch. 26/1, Sonderheft, 165-176 (1971). Menge/, K., Grimme, H. und Nemeth, K.: Potentielle und effektive Verftigbarkeit 'Ion Pflanzennahrstoffen im Boden. Landw. Forsch. 23/1, Sonderheft, 29-91 (1969). Mengel, K.: Ernahrung und StofTwechsel der Pflanzen. Fischer-Verlag Stuttgart. 1972. Nemerh, K.: The determination of desorption and solubility rate of nutrients in the soil by means of electroultrafiltration. In 'Potassium in Soil', Intern. Potash Inst. Bern, 171-180 (1972). 62
Nye, P. H.: Localised movement of potassium ions in soils. In 'Potassium in Soil', Intern. Potash Inst. Bern, 147-1.5.5 (1972). Grajvon Reichenbach, H.: Factors of mica transformation. In 'Potassium in Soil', Intern. Potash Inst. Bern, 3]-42 (1972). Rich, C. I.: Potassium in soil minerals. In 'Potassium in Soil', Intern. Potash Inst. Bern, 1.5-31 (1972). Schroeder, D.: Bodenkunde in Stichworten, Hirt-Verlag Kic1, 2nd ed., 1972. Schuffelen, A. c.: The cation exchange system of the soil. In 'Potassium in Soil', Intern. Potash Inst. Bern, 7.5-88 (1972). Tepe, W. und LeidenjroJ/, £.: Ein Vergleich zwischen pflanzenphysiologischen, kinetischen und statischen Bodenuntersuchungswerten. Landw. Forsch. 11, 217-229 (19.58). Tinker, P. B.: Studies of soil potassium IV. J. Soil Sci. 15, 3.5 (1964). Tinker, P. B.: Potassium uptake rates in tropical crops. In 'Potassium in Tropical Crops and Soils', Intern. Potash Inst. Bern, 117-122 (1973). V/rich, B.: Boden und Pftanze, Enke-Verlag Stuttgart, 1961. Wild, A., Rowell, D. L. and Ogunjowora, M.A.: The activity ratio as a measure of the intensity factor in potassium supply to plants. Soil Science /08,432-439 (1969). 63
Page 2 and 3: Potassium Research and Agricultural
Page 4 and 5: Chaudet, P. 1st Working Session SOD
Page 6: Drouineau, G. Mathieu, M. Mafavofta
Page 11 and 12: Chairman: Co-ordinator: 1 si Workin
Page 13 and 14: of the agricultural wage-earners wa
Page 15 and 16: for certain industrial crops a mino
Page 17 and 18: expected to produce fertilizer type
Page 19 and 20: Organization and Achievements of Ag
Page 21: Research expenses are distributed a
Page 24 and 25: vigorously cultivated. The intensiv
Page 26 and 27: It became clear that in Congresses
Page 28: this balancing effect. On the other
Page 32 and 33: problems were studied by field and
Page 35 and 36: There is need to relate fertiliser
Page 37: Increase in the fertilisers used in
Page 42 and 43: are easier to use than three separa
Page 44 and 45: of workers, preferably associated b
Page 46 and 47: Chairman: Co-ordinator: 2 nd Workin
Page 49 and 50: Accordingly, K release increases fr
Page 58 and 59: The Use of Reagents Containing Sodi
Page 60: tiated by the cultivation practices
Page 63 and 64: terial being an eruptive or crystal
Page 66: G. Dut/lion, C. and Grosman, Ruth:
Page 76 and 77: Potassium Fixation and Assessment o
Page 79: The quantitative and qualitative di
Page 84: Table 6. Average dry matter yield i
Page 95: tons in 1960 in Hungary. Rapidly in
Page 99: Bibliography I. KOIak. M.: Study of
Page 106 and 107:
Interaction of Potassium, Magnesium
Page 110 and 111:
3.3. Influence 0/ K, Alg alld Ca do
Page 116:
Table 8. (Lehmann. Malysirlk (15])
Page 123:
the magnitude of these reserves may
Page 132 and 133:
than a plant rich ill carbohydrates
Page 135:
form. Up to now wc do not know of o
Page 138:
Improvement of potassium nutrition
Page 145:
ATP Synthesis and Assimilate Transp
Page 151 and 152:
38 36 32 30 28 26 r Fig. J. x y •
Page 158:
Potassium and the Nutritive Balance
Page 170:
account of the unfavourable results
Page 176:
thorough understanding of the funct
Page 181:
Table 4. Nand K contents in milligr
Page 189 and 190:
In our view the fact that the K ion
Page 193 and 194:
[29]), suggesting that the K defici
Page 195:
eral sites permitting hydrogen-bond
Page 198:
Ions may be appreciably retransloca
Page 201:
would suggest that translocation is
Page 207 and 208:
Absorption and Lateral Transport of
Page 210:
cells and intracellular ,K+ activit
Page 224:
a value between the optimum and 1.0
Page 232 and 233:
the optimum (2.34%). Leaves affecte
Page 234 and 235:
!, 42 0,2u QII: laD l,Ra VfMl /91a
Page 237:
During the course of the years as t
Page 240 and 241:
Or. A. Vakhimstrov pointed out the
Page 242 and 243:
Summary Assessment of Potassium Fer
Page 245:
population the same imbalanced situ
Page 249:
Table 6. Responses of rice in soil
Page 253:
Table 10. Effect of potassium on th
Page 259 and 260:
12. Groundnut Groundnut is generall
Page 261:
Such a heavy production per hectare
Page 266 and 267:
sic primary minerals such as felspa
Page 268 and 269:
tween yield and K content of leaves
Page 270 and 271:
soils cannot therefore give any val
Page 272 and 273:
Summary Recent Developments of K Fe
Page 274 and 275:
5 FiK. 1. Soil regions of Latin Ame
Page 276:
N ... '" 7. Lower Amazon and J lowe
Page 280 and 281:
Table 2-3. Quantities of elements e
Page 285:
Ratio 1973 Time Fig. 5. Trends in r
Page 292 and 293:
Summary Intensification of Agricult
Page 295 and 296:
w ..,. Relative yield 100 " 80 70 5
Page 297 and 298:
agement practices, and without natu
Page 300 and 301:
(c) Nigeria, savanna zone (Healhcol
Page 302:
2.4. Improved ·/allows' If a plant
Page 305 and 306:
Report of the Co-ordinator of the 4
Page 307 and 308:
eached where the land is continuous
Page 309 and 310:
Chairman: Co-ordinator: 5 th Workin
Page 311 and 312:
kg/ha 5000 4000 3000 2000 1000 o Ge
Page 313 and 314:
Pollution caused by fertilizer is t
Page 315 and 316:
Thus, even relatively high nitrate
Page 317:
Table 4. Distribution of the potass
Page 321:
The Table shows, that even sand fro
Page 324:
This indicates that potassium uptak
Page 328 and 329:
6. Vollen'lf.'cidcr Rich.A.: Scient
Page 330 and 331:
Report of the Co-ordinator of the 5
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