(Jbotak IR Enem

(Jbotak IR enem Monthly communications by the International Potash Institute, Berne (Switzerland) Subject 4 Soil Science April 1965 34th suite The Fixation, Accumulation and Depletion of Potassium in Lowland Rice Soils M. P. Feng and S.C. Chang' From: Memoirs of College of Agriculture, National Taiwan University, Taipei, Vol. 8, No. 1 (1964) Analyses of a large number of paddy soil samples representative of the main soil groups in Taiwan, from acidic Latosols to calcareous alluvial soils, reveal that the contents of exchangeable potassium are generally low, from 50 to 80 ppm, and rather uniform among soil groups, while those of non-exchangeable potassium are much higher and vary considerably among soil groups (Chang and Feng, 1960). Studies on the soils from a long-term fertilizer experiment of lowland rice show that neither the depletion of exchangeable and non-exchangeable potassium in the no-potassium plot nor the accumulation in the potassium-treated plot is noticeable (Chang and Chu, 1960). All these data suggest that the equilibrium of the various forms of potassium in flooded soils must be different from that in upland soils. Systematic data on this subject are, however, scanty.The purpose of this paper isto make a preliminary study with regard to the fixation, accumulation and depletion of potassium in a number of soils of Taiwan under flooded condition for rice growing. Materials and Methods Three series of experiments are included in this investigation. Soil samples taken from the plots of nine long-term experiments of potash fertilizer conducted on representative soils of Taiwan were used to observe the change of exchangeable and non-exchangeable potassium resulting from different fertilizer treatments. These long-term experiments were started in 1958 or 1959. Samples of surface soils and subsoils were collected after the harvests of the second crop of rice each year successively for the last three years from 1959 through 1961. The general properties of the nine soils and two other soils which were used in the later part of this investigation are shown in Table 1. The fixation of potassium was studied on five representantive soils from Chunglee, Taoyuan, Taichung, Yuanlin and Hsinying, respectively. Potassium at rates of 200 and 400 ppm was added to the soils. The soils were kept under four different moisture conditions for three months. The soluble and exchangeable potassium was determined, and the fixed potassium calculated to study the distribution of the added potassium into these various forms. Research Assistant, and Professor, Soils and Plant Nutrition Laboratory of National Taiwan University, Taipei, Taiwan. Date received for publication: February 10, 1964. 1 ... The release of potassium under excessive leaching was studied with four soils from Chunglee, Taichung, Yuanlin and*Hsinying. 400 ppm of K was added to each soil on a Buchner funnel and kept under continuous flooding and percolation by adding water to the funnel as needed. Soluble potassium was determined in successive 200 ml portions of leachate for five times. The total number of days needed to collect 1000 ml of leachate is around 10 days for the soils of Chunglee and Tai- chung, 20 days for the soil of Yuanlin and 40 days for the soil of Hsinying. The exchangeable and non-exchangeable potassium of the treated soil was also determined. Table 1 General properties of the soils used Dominant Organic clay Locations Soil groups Texture pH matter (%) minerals Chunglee Latosol Silty clay loam 4.7 2.0 Kt' Nanshi Latosol Silty clay loam 4.9 1.3 Kt Taoyuan Latosol Silty clay loam 4.9 2.2 Kt Taipei Sandstone and shale Silt loam 4.8 2.5 Kt, It alluvial soil Hsinchu Sandstone and shale Silt loam 6.1 3.1 Kt, It alluvial soil Miaoli Sandstone and shale Sandy loam 5.9 1.2 Kt. It alluvial soil Hsinhua Sandstone and shale Silt loam 6.1 1.2 Kt, It alluvial soil Yuanlin Slate alluvial soil Silt loam 7.5 2.1 It Silo Slate alluvial soil Silt loam 6.4 2.1 It Pingtung Slate alluvial soil Silt loam 6.2 1.9 It Hsinying Mudstone alluvial soil Silty clay loam 7.3 2.1 It " Soil: H.O is I : 1. " Kaolinite S]llite Throughout this investigation, soluble, exchangeable, and non-exchangeable potassium was extracted by water, neutral N ammonium acetate (Schollenberger, 1945), and sulphuric acid (Hunter and Pratt, 1958), respectively. The potassium in the extract was determined flamephotometrically. Results and Discussion The exchangeable and non-exchangeable potassium in the soils sampled from the fields of nine potash fertilizer experiments in three representative soil groups are presented in Table 2. In the potassium-treated plots. 80 kg/ha of K2O or 33 ppm of potassium on the basis of 2 000 000 kg/ha of furrow slice of soil, were applied for each crop. There- fore, the total potassium applied for the experiments started from the second crop of rice of 1958 is equivalent to 231 ppm (7 crops), and that for experiments started from the first of 1959 is 198 ppm (6 crops). A perusal of the figures in Table 2 shows that the tendency of accumulation and depletion of potassium in the soils, year by year, is not consistent, yet the tendency does show that neither depletion in the no-potassium plots nor accumulation in the potassium-treated plot is signifi- 2 (J~task (Retiew Monthly communications by the International Potash Institute, Berne (Switzerland) 4/34 Table 2 Exchangeable and non-exchangeable K in the soil sampled in successive years Location of Treat- Exchangeable K ppmO Non-Exchangeable K ppmn experiments ments Soil layers 1959 1960 1961 Average 1959 1960 1961 Average K Surface soil 56 61 60 59 61 72 53 62 K. 1 Subsoil 44 44 39 42 56 79 61 65 Surface soil 66 66 91 74 62 72 42 59 h e Subsoil 44 49 58 50 66 74 55 65 fhnlrSurface soil 59 84 60 66 61 64 53 599 MK. 1 Subsoil 41 46 41 43 57 79 59 65 Surface soil 76 95 94 88 62 65 51 59 Subsoil 44 74 59 59 69 64 64 66 Surface soil 75 81 69 75 93 82 91 90 K. ( Subsoil 74 69 66 70 106 91 74 90 92 92 94 K Surface soil 91 98 103 97 99 Subsoil 86 69 81 79 109 96 89 98 Nanshi M Surface soil 91 79 86 85 99 111 74 95 MK. N Subsoil 86 58 71 72 99 122 84 102 100 66 82 MK. Surface soil 105 95 124 103 80 Subsoil 89 61 76 75 81 119 69 90 Surface soil 54 40 35 43 96 90 105 97 K. Subsoil 49 40 33 41 149 125 150 141 Surface soil 55 40 41 45 115 110 104 110 I Subsoil 43 40 33 39 157 156 142 151 Taipei Surface soil 50 38 38 42 95 117 90 101 Subsoil 43 40 31 38 147 160 139 149 116 100 106 m Surface soil 58 44 45 49 102 Subsoil 43 38 31 37 147 170 149 155 Surface soil 50 46 41 46 150 164 194 169 K. Subsoil 49 43 35 42 159 190 208 186 K. Surface soil 50 50 49 50 160 180 186 175 163 207 218 196 in K Subsoil 50 46 35 44 160 184 166 MK. Surface soil 45 53 46 48 155 Subsoil 49 44 35 43 176 181 208 188 153 162 186 167 MK. Surface soil 55 58 54 56 Subsoil 45 44 39 43 175 169 209 184 Surface soil 23 34 25 27 50 54 53 52 K. Subsoil 23 53 20 32 50 70 50 57 Surface soil 25 53 30 36 58 70 58 62 Miaoli K, Subsoil 21 34 21 25 52 51 52 52 50 54 MK. Surface soil 24 28 25 26 56 55 Subsoil 21 23 21 22 57 50 52 53 Surface soil 28 28 34 30 60 57 54 57 Subsoil 24 21 26 24 59 59 47 55 3 Location of Treat- Exchangeable K ppm' Non-Exchangeable K ppm' experiments ments' Soil layers 1959 1960 1961 Average 1959 1960 1961 Average Surface soil 33 60 36 43 150 158 154 1 Subsoil 38 50 44 44 245 265 269 260154 K= j Surface soil 30 43 35 36 165 155 160 160 HsKnhu Subsoil 36 43 38 39 257 220 230 236 Surface soil 29 50 34 38 164 168 179 170 MK. Subsoil 36 44 38 39 242 236 230 236 MK J Surface soil 33 35 35 34 170 185 155 170 Subsoil 36 38 35 36 242 243 218 234 K. Surfacesoil Subsoil 24 20 26 23 109 108 107 103 K 23 18 23 22 130 152 144 142 K2 Surfacesoil 28 20 26 25 117 115 124 119 YuaKlin Subsoil 23 18 23 22 127 152 146 142 MK. Surface soil 25 23 26 25 115 110 116 114 Subsoil 24 23 24 24 129 152 146 142 MK, Surface soil 28 29 28 28 122 111 127 120 Subsoil 25 21 25 24 135 154 150 146 K. Surface soil 34 44 54 44 179 181 166 K Subsoil 33 175 40 38 37 185 213 182 193 K2 Surface soil 38 46 55 46 175 182 193 183 Silo Subsoil 34 40 39 38 194 203 234 210 MK. Surface soil 40 43 40 41 173 182 173 176 ( Subsoil 35 40 38 38 195 208 222 208 K{ Surface soil 40 46 49 45 176 197 194 189 Subsoil 34 38 39 37 189 192 214 198 Surface soil 35 35 33 34 143 178 147 156 K Subsoil 28 29 33 30 180 239 220 213 K.

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