JOURNAL OF THE SCIENTIFIC AGRICULTURAL SOCIETY OF FINLAND Maataloustieteeilinen A ikakauskirja 371 Voi. S4: 371-383, 1982 The efficiency of dolomitic limestone, basic slag and peat ash as liming agents, and as calcium and magnesium sources for turnip rape RAILI JOKINEN University of Helsinki, Department of Agricultural Chemistry, 00710 Helsinki 71, Finland Abstract. Incubation and pot experiments were carried out on muddy fine sand and fine sand soils to determine the efficiency of dolomitic limestone and of industrial by-products, basic slag and peat ash, as liming agents. Calcitic limestone was used as reference material. In the incubation experiment 0, 0.6, 1.2 and 2,4 g calcitic limestone were applied to 390 g (muddy fine sand) or 360 g (fine sand) of air-dry soil. The amount of other liming agents added was 2.4 g. In the pot experiment the weights of soil were 3.9 kg (muddy fine sand) and 3.6 kg (fine sand) and 24 g of liming agent was applied. The turnip rape ( Brassica campestris v. oleifera f. annua cv. Candle) was grown in two growing seasons and the crops were cut at the flowering stage. In both experiments the soils were sampled for analysis after four and sixteen months. The acidity of the soils was neutralized with the liming agents to the same extent in the pot and the incubation experiments. The increases in pH(CaCh) obtained in the incubation experiment with 2.4 g liming agents were on the muddy fine sand and fine sand for calcitic limestone 2.0 and 1.4, for dolomitic limestone 1.5 and 1.1, for peat ash 0.3 and 0.2, for basic slag 0.8 and 0.6, respectively. At the end of the incubation 2.4 gof dolomitic limestone, peat ash and basic slag had increased the pH(CaCl2 ) of the soils to the same extent as 1.7 g, 0.4 g or 0.8 g of calcitic limestone, respectively. The proportion of non-exchangeable Ca at pH 7 of the amount added in 2.4 g liming agents was for calcitic limestone 14 and 23 %, for dolomitic limestone 42 and 52 %, for peat ash 27 and 51 %, and for basic slag 59 and 64 %, in the muddy fine sand and fine sand soils, respectively. Of the Mg added in dolomitic limestone, about 45 % was non-exchangeable, and in basig slag about 65 %. In the pot experiment about 13 % (average of the two soils) of the Ca applied in calcitic limestone was not found in turnip rape or as neutral 1 M ammonium acetate extractable from the soil. The corresponding value for dolomitic limestone was 41 %, for peat ash 45 % and for basic slag 65 %. The Mg applied in the liming agents but not found in turnip rape or in the soil amounted to 42 % for dolomitic limestone, 74 % for peat ash and 67 % for basic slag. The efficiency of basic slag as a liming agent will be overestimated if it is measured by the amount of acid neutralized or by the content of Ca and Mg (Ca + I.6sxMg) soluble in 1 M HCI. The amount of Ca soluble in 1 M HCI, alone, may provide a better, though not good, measure of the neutralizing ability of basic slag. Introduction Calcitic and dolomitic limestones are the most widely used liming agents in Finnish agriculture. Basic slags, by-products of the iron and steel industry, https://www.c-info.fi/en/info/?token=4rCK30SdSUuwl750._G1KJdnfdrt0I7OMeQAbIg.Wz0ew0xQby9VuwLQP5Y6WWGVyXblh_LECOKLzwo1PA7reaGRWjWR8X2PuIthd14cEKOqPextw-WJkyBY6wvdBLILK-dxD6X7f1dBDsEgl6nPn_RBwHSBTe3wYVlpbyZ8G2tN8wbQfq1aFN4F5BApk2GvW7jRr1d-zXSO 372 have a local use. In future peat will be used as a fuel in power plants and the supply of peat ash to agriculture can be expected to increase. The original Bessemer process gave basic slag with a high content of phosphorus (Thomas slag) and its main use in agriculture was as a phos- phorus fertilizer. Recent developments in the process are designed to pro- duce slags of low phosphorus content (BROWN and THATCHER 1969) and the basic slags are now principally only liming agents. The efficiency of basic slag and peat ash as liming agents has been little studied. NORRMAN (1978) supposed silicatic liming agents (slags) to be able to neutralize the acidity of soil equivalently to carbonatic agents (limestones) if the total content of Ca in the slag was over 30 %. The results of BUCHER (1951) revealed that in acid soil the neutralizing capacity of slag was weaker than that of calcitic limestone when both were ground to the same fineness. The purpose of the present investigation was to study the effects of fine ground basic slag and peat ash on the pH(CaCl 2 ), on the effective cation exchange capacity and on neutral 1 M ammonium acetate extractable Ca, Mg and K contents of two acid soils in incubation and pot experiments, and to compare the effects with those of calcitic and dolomitic limestones. The availability of Ca, Mg and K of these liming agents for turnip rape (Brassica campestris v. oleifera f. annua) was studied in the pot experiment. Materials and methods Two topsoils (volume 500 1) were taken from the cultivated area of the Viikki Experimental Farm (University of Helsinki) for the experiments. Both soils were acidic, the main difference being the higher content of organic carbon in the fine sand (Table 1). The muddy fine sand was a post glacial deposit (Littorina Sea) near the Gulf of Finland. Calcitic and dolomitic limestones (here referred to as lime and dolomite, resp.) were commercial Finnish products. Basic slag (slag) was process slag from the iron industry, cooled with water and ground. Peat ash (ash) from a peat power plant was a grate ash, containing 63 % sand. The properties of the liming agents are presented in Table 2. The pot experiment was performed in Mitscherlich-pots in the years 1980 and 1981. The pots were kept out of doors in a netwalled hall provided with a polycarbonate roof. Between the two growing seasons the pots were covered. Each pot was filled with 4.5 kg of moist soil (in air-dry state the weight of muddy fine sand 3.9 kg and fine sand 3.6 kg), and the soil treated with 24 g of liming agent and the following amounts of nutrients: 1000 mg N as NH4N0 3 , 400 mg P and 1000 mg K as K 2 HP04 , 10 mg B as H 3 B03 , 15 mg Cu as CuS04-5H 20, 10 mg Mn as MnS0 4-4H 20, 10 mg Zn as ZnS0 4-7H 20 and 5 mg Mo as Na2 Mo0 4 -2H2 0. The nutrient tretment in the second spring was the same as in the first. Liming treatments were made in the first spring only. In addition to the limed soils the experiment included control soils without added liming agents. All treatments were repeated four times. Turnip rape (cult. Candle) was sown at a density of 20 seeds per pot two days after liming and fertilization. Twenty days after germination the plants were thinned to nine. The crops were cut in the first year at the end of flowering and in the second year at the beginning of flowering. The incubation experiment was performed in Vi 1 plastic pots, into each of which 450 gof soil (in air- dry state 390 g of muddy fine sand and 360 g of fine sand) was weighed. The following liming treatments were made: no liming, 0.6 g, 1.2 gor 2.4 gof lime, 2.4 gof dolomite, 2.4 gof ash and 2.4 gof slag. The soils were supplemented with nutrients N, P, K, B, Cu, Mn, Zn and Mo in amounts 1/10 of those applied in the pot experiment. The soil moisture was regulated with de-ionized water to 25 %of the air-dry soil and maintained near this level with monthly waterings. The incubation was continued for 16 months. For four months (May-August 1980) the pots were outdoors in the nethall, for the next eight monts (September 373 Table I. The properties of the soils Muddy Fine fine sand sand Particle size distribution, % <2 pun 22 23 2-20 pun 19 12 20-200 pun 57 58 >2OO pun 2 7 Org. C, % 3.0 6.4 pH(CaCl2) 4.8 4.8 Exchangeable (pH 7) cations, me/kg soil Ca2+ 56 95 Mg 2+ 13 9 K + 6 9 Na + 3 2 Effective cation exchange capacity, me/kg soil 76 102 1 M KCI extractable (Al+H), me/kg soil 9 7 Table 2. Liming materials Calcitic Dolomitic Peat Basic limestone limestone ash slag (lime) (dolomite) (ash) (slag) Acid neutraliced equivalent to Ca, % 39.4 37.2 9.6 31.1 1 M HCI soluble Ca, % 37.0 18.6 5.5 20.6 Mg, % 1.1 10.8 0.5 5.6 K, % 0.04 0.12 0.24 0.47 Neutralizing ability Ca4-I.6sxMg, % 38.8 36.4 6.3 29.8 Sieve analyses, % <0.125 mm 5.4 0.125—0.250 mm 50.9 0.250-0.500 mm 13.8 0.500-1.000 mm 28.6 >l.OOO mm 1.3 1980-April 1981) inside at constant temperature +5 °C, and during the final four months (May-August 1981) again outdoors. Each pot was covered with perforated plastic film and all the pots together with black plastic film, as a shelter against the light. Analyses: The liming agents were analyzed for 1 M HCI soluble Ca, Mg and K, and the ’’neutralizing ability” Ca + I.6sxMg was calculated in per cent. The amount (me) of 1 M HCI neutralized with the liming agents was also determined and calculated as Ca %. The slag was sieved and the sand content of the peat ash was weighed. After harvesting, the plant material was kept at 60 °C until dry and then heated at 105 °C two hours. For the analyses the plant material was ground with a Willey-mill. Wet combustion procedure with the acid mixture HCIO, : H 2SO, : HNO, (1:2.5:10) was performed (SCHARRER and MUNK 1956), The total contents of Ca and Mg were determined by atomic absorption spectrophotometry (Varian 1000) with interference element La and total content of K was determined by flame photometry (Lange, model 6). The soils of the pot experiment were sampled shortly after the two harvestings and those of the incubation experiment at equivalent times (after 4 and 16 months incubation). The neutral 1 M ammonium acetate extractable (exchangeable in pH 7) Ca, Mg and K contents (method described by JOKINEN 1981), the effective cation exchange capacity (ECEC) and 1 M KCI extractable (Al+H) content (KAILA 1971), and the pH(CaCl 2) were determined from air-dry soils. Statistics: The significant differences between the liming treatments were estimated by Duncan’s new multiple range test (STEEL and TORRIE 1960). In the tables the results of individual soils signified with a common letter do not deviate significantly (P=0.05). Results Incubation experiment The increases in pH(CaCl 2) obtained with the three levels of lime seemed to be a little lower in fine sand soil than in muddy fine sand (Table 3). This was probably because of the higher organic carbon content of the fine sand. On the basis of the pH(CaCl2 ) values obtained without liming and with three levels of lime, a ’’neutralizing line” was drawn. The equivalent amounts of lime giving the same pH(CaCl2 ) as 2.4 g other liming agents were then Table 3. The pH(CaCl2 ), the ECEC (me/kg soil), the 1 M KCI extractable Al+H (me/kg soil) and exchangeable (pH 7) Ca and Mg (mg/kg soil) in the soils without liming and with four liming agents after four and sixteen months incubation. Incubation time, months 4 16 4 16 4 16 4 16 4 16 4 16 ECEC Al+H Ca Mg K pH(CaCl 2 ) me/kg soil me/kg soil mg/kg soil mg/kg soil mg/kg soil Muddy fine sand No liming 4.3* 4.4* 82* 80* 15.0f 15.4* 1113* 1166* 166* 166* 486 c 449d Lime 0.6 g 5.1* 5.0* 96* 97* 5.1d 4.9' 1600 d 1720b 176* 177b 439*b 428b * Lime 1.2 g 5 .7* 5.6' UT- 120** 3.0* 2.8* 2063' 2281* 180* 182b 447b 415* b Lime 2.4 g 6.5* 6.4* 143' 150* 1.2* 1.6* 2758 d 3132 d 175* 177b 413* 409* Dolomite 2.4 g 5.9' 5.9’ 118d 125' 2.2b 2.3 b 1627 d 1826 b 449* 527d 442*b 424*b* Ash 2.4 g 4.6 b 4.7b 87b 87b 9,9' 9,2 f 1253 b 1413* 171* 182 b 477* 456d Slag 2.4 g 5.1* 5.2 d 97* 101* 5.1d 3.8d 1494* 1685b 271 b 288* 462b* 439*d Fine sand No liming 4.4* 4.5* 117* 119* 12.0' 11.4* 1731’ 2043* 120* 141* 631 b 567* Lime 0.6 g 5.0* 4.9b 139* 136* 5.2* 5.2d 2256* 2556* 126* 139* 584* 566* Lime 1.2 g 5.4 d 5.3 d 161 d 160' 4.2b* 3.7b 2779d 3101 d 132* 144* b 606*b 563* Lime 2.4 g 5.9 1 5.9 f 197' 190* 2.6* 2.7* 3747* 3935' 140* 147** 612*b 570* Dolomite 2.4 g 5.5' 5.6' 157d 1671 3.4*b 3.3 b 2324' 2642* 411* 520 d 587* 564’ Ash 2,4 g 4.6 b 4.8b 125b 124b 10.0d B.l' 2006 b 2223b 131* 147b 632b 577* Slag 2.4 g 5.0* 5.1* 138* 145d 5.6' 4.5* 2163* 2538* 217 b 265* 605*b 574* 374 375 read from the line. After 16 months incubation the following increases in pH(CaCl2 ) and lime equivalents were found: Muddy fine sand Fine sand Increase Equivalent Increase Equivalent in pH(CaCl2) lime g in pH(CaCl2) lime g Dolomite 1.5 1.6 1.1 1.8 Ash 0.3 0.3 0.2 0.4 Slag 0.8 0.8 0.6 0.8 For equal increases in pH(CaCl 2) on both soils the amount of dolomite needed was about 40 % higher than the amount of lime, the amount of ash about sevenfold the amount of lime and the amount of slag about threefold the amount of lime. When the amount of acid neutralized by lime (as Ca, %), the neutralizing ability (Ca + I.6sxMg, %) and the 1 M HCI soluble Ca content (Ca, %) of the lime are each indicated by 100, the respective properties of the other liming agents obtained are the values given below. The increases in pH(CaCl2 ) obtained with 2.4 gof liming agents are shown in columns 4 and 5. Acid Soluble in 1 M HCI Increases in pH(CaCl2 ) neutral. Ca+l.6sxMg Ca Muddy Fine as Ca, % % % fine sand sand Lime 100 100 100 2.0 1.4 Dolomite 94 94 50 1.5 1.1 Ash 24 16 15 0.3 0.2 Slag 79 77 56 0.8 0.6 In this comparison it was assumed that after 16 months incubation all the lime applied would be reacted in the soil. The difference between the values determined in the laboratory and measured in the experiment was largest for slag. Evidently the amount of Ca soluble in 1 M HCI is a better measure of the neutralizing ability of the slag than are the other properties analyzed. All three methods gave equivalent information for the ash. The differences for dolomite and lime are similar to those obtained in earlier studies (JAAKKOLA and JOKINEN 1980, JOKINEN 1982). The ECEC was highest in soils treated with 2.4 g of lime (Table 3). After 16 months the increase in ECEC brought about by 2.4 g of dolomite was equivalent to 1.4 g of lime. The corresponding results for ash and slag were 0.3 and 0.75 g, respectively. These values are the means of the two soils, since there were no differences between them. In muddy fine sand there seemed to be a slight increase in ECEC between 4 and 16 months incubation when the soil was treated with dolomite or slag. This may point to a slower dissolution of these liming agents than of lime and ash. At the end of the incubation the 1 M KCI extractable (Al+H) content of the soils treated with 2.4 g slag was equivalent to 0.9 g of lime, with dolomite equivalent to 1.6 g lime and with ash equivalent to 0.4 g lime. The proportion of Al to the (Al+H) was in unlimed muddy fine sand about 6 % and in unlimed fine sand about 5 %. In the limed soils the proportion of Al varied from 0.7 % (lime 2.4 g) to 5.2 % (ash 2.4 g). The efficiency of dolomite, ash and slag as liming agents relative to lime, measured on the basis of ECEC and of 1 M KCI extractable (AI4-H), corroborates the evaluation made on the basis of pH(CaCl2 ). In comparison with the original condition, the pH(CaCl2 ) of unlimed soils was decreased and the content of (AI+H) increased during the incuba- tion. Further the conductivity in incubated muddy fine sand was 5.5 yu,S and in fine sand 6.5 yu-S; in the original soils the conductivities were 0.8 yuS, and 0.5 yu,S, respectively. All these changes in soil properties were attributable to the nutrient treatments. The exchangeable Ca content of the soils when treated with 2.4 g of slag was the same as with 0.6 g lime (Table 3). On muddy fine sand the ash had no significant effect on the Ca content, and on fine sand the Ca content was a little higher than without liming. Dolomite gave the same exchangeable Ca contents as 0.6 g lime. At the most, 14 % of the 1 M HCI soluble Ca added in lime to the muddy fine sand was non-exchangeable at the end of the experiment (Table 4). The corresponding result for the fine sand was 23 %. On both soils the propor- tion of the non-exchangeable Ca of that added in dolomite, ash and slag was Table 4. The amounts of 1 M HCI soluble Ca and Mg (mg/kg soil) added with liming agents and the proportion (%) of the non-exchangeable (pH 7) cations in the soil out of the added at the end of the incubation experiment. Calcium Magnesium Non-exchange- Non-exchange- Limings Added able (pH 7) Added able (pH 7) mg/kg mg/kg % mg/kg mg/kg % Muddy fine sand Lime 0.6 g 569 15 3* 17 6 35‘ Lime 1.2 g 1139 24 2“ 34 18 52bc Lime 2.4 g 2277 311 14b 65 54 83d Dolomite 2.4 g 1145 485 42 d 662 301 45“ b Ash 2.4 g 338 91 27' 32 16 50“ b Slag 2.4 g 1268 749 59' 342 220 64c Fine sand Lime 0.6 g 617 104 17“ 18 20 III d Lime 1.2 g 1233 175 14“ 37 34 92 c Lime 2.4 g 2467 575 23“ 73 67 92 c Dolomite 2.4 g 1240 641 52 b 717 338 47“ Ash 2.4 g 367 187 51b 35 29 83c Slag 2.4 g 1373 878 64 b 370 246 67b 376 377 significantly higher than in lime. Over 60 % of the 1 M HCI soluble Ca of slag was non-exchangeable after 16 months incubation. Equal amounts of 1 M HCI soluble Mg were added in 2.4 g ash and 1.2 g lime. At the end of incubation the exchangeable magnesium content of these treatments did not deviate significantly (Table 3). The exchangeable mgnesium content of soils limed with slag was lower than of soils limed with dolomite, since the amount of 1 M HCI soluble magnesium added was about 50 % of the magnesium added in dolomite. The increasing amount of lime (containing 1.1 % Mg) had no significant effect on the exchangeable Mg content of the soils. The fixation of Mg to non-exchangeable form was not observed in this incubation experiment. The 0.01 M CaCb extractable Mg decreased with increasing amounts of lime (results not presented). After four months incubation about 58 % of the Mg applied in dolomite was non-exchangeable and after 16 months about 46 % (Table 4). The corresponding figures for slag were 71 and 65 %. In relative terms the release of Mg from slag was less than from dolomite. The release of Mg took place during the whole experimental period but was slower in the period between 4 and 16 months. The exchangeable (pH 7) K content of the soils decreased with increasing amounts of lime as a result of the fixation to non-exchangeable (Table 3). The K applied in slag and ash maintained the K content of the soils at that level of unlimed soils, or these liming agents did not promote the fixation of K into non-exchangeable form. Pot experiment The treatments with 24 g of lime, dolomite, ash or slag did not cause any significant differences in the yields of turnip rape harvested at the flowering stage (Table 5). Relative to the unlimed control slag and ash had no effect on the Ca content of the turnip rape in either year (Table 5). Dolomite was as effective as lime in increasing the Ca content of yields, except in the fine sand in the second growing season. The K applied in slag or ash did not cause any changes in the K content of turnip rape (results not presented). The highest Mg content of turnip rape was obtained with dolomite and the lowest with lime in both growing seasons (Table 5). Relative to the unlimed control the Mg content of plants produced with slag was signifi- cantly higher; liming with ash had no effect on the Mg content of turnip rape. On both soils the Ca uptake by turnip rape (total in two years) was almost the same with dolomite and slag (Table 6). All liming agents studied increased the Ca uptake by turnip rape but most of all lime. The apparent recovery of the Ca applied in dolomite and slag was lower than in lime and ash. The total amount of Mg taken up by turnip rape was the same without 378 Table 5. The yields of turnip rape at the floweringstage (g/pot), and the total contents of Ca and Mg (mg/g dry matter) in plant material obtained without liming and with four liming agents in first and second growing seasons. Yield g/pot Ca mg/g Mg mg/g Ist 2nd Ist 2nd Ist 2nd Muddy fine sand No liming 33.4' 19.7' 16.2* 16.3'b 2.2ab 2.7b Lime 41.0* 23.3' 27.2b 22.1 c 1.6' 2.0' Dolomite 32.4' 19.0' 21.7'b 20.1 bc 3.8 C 4.9d Ash 36.6' 22.5' 17.4' 14.1“ 2.1'b 2.2“ Slag 36.0' 24.8' 17.9' 15.5' 2.5b 3.1c Fine sand No liming 30.9' 28.1' 19.7“ 14.0' 1.6“b 1.6' Lime 35.6“ 31.0' 28.8b 18.5b 1.3' 1.4“ Dolomite 34.0' 30.7“ 22.3“b 14.3' 2.9C 3.3C Ash 36.9' 30.4' 18.2“ 14.9' 1.4' 1.6' Slag 32.2' 32.4' 21.3' 15.4' 1.9b 2.3 b liming and with lime or ash (Table 6). Turnip rape was not able to utilize Mg applied in these liming agents. The apparent recovery of Mg from dolomite and slag amounted to 3-4 %. The increases in Mg uptake due to slag and dolomite were significant. The exchangeable (pH 7) Ca content was highest in the soils treated with lime because of the great amount of Ca added in this material (Table 6). Though dolomite contained a lesser amount of 1 M HCI soluble Ca than slag, the exchangeable Ca content of the soils treated with dolomite was signifi- cantly higher. Neither lime nor ash had any effect on the exchangeable Mg content of the soils (Table 6). The amount of 1 M HCL soluble Mg added to the soils in slag was about 50 % of the amount added in dolomite. The increase in exchangeable Mg content of the soil was with slag about 30 % of the increase obtained with dolomite. In the pot experiment about 13 % of the Ca added in lime was not found in the yields or in exchangeable form in the soil (Table 6 ). The corresponding result for dolomite was about 40 %, for ash about 45 %, and for slag about 65 %. About 43 % of the Mg applied in dolomite, 67 % of that added with slag and 75 % of that added with ash were not in the yields or in exchangeable form in the soils. At the termination of the pot experiment the pH(CaCl 2) of the soils was almost the same as in the incubation experiment. The greatest increase in pH(CaCl 2 ) was measured in the soils treated with lime and the increase diminished in the order dolomite > slag> ash (Table 7). The effect of liming agents on the pH(CaCl2 ) was weaker on fine sand soil rich in organic carbon than in muddy fine sand. The ECEC of muddy fine sand did not change upon application of peat ash (Table 7). With other liming agents the increases in ECEC were analo- gous to the increases in pH(CaCl 2 ) on both soils. 379 Table 6. The amounts of Ca and Mg (mg/kg soil) applied with liming agents, the total Ca or Mg uptake (mg/kg soil) by turmip rape, the exchangeable (pH 7) Ca and Mg contents (mg/kg soil) of the soils and the proportion (%) of added Ca or Mg not found in the yields or exchangeable in the soils (=non-exchangeable) at the end of the pot experiment. Calcium Magnesium Added Uptake Ex- Non- Added Uptake Ex- Non- in by change- ex- in by chhange- ex- liming turnip able change- liming turnip able change- agents rape (pH 7) able agents rape (pH 7) able mg/kg soil % mg/kg soil % Muddy fine sand No liming 215* 916* 32* 125* Lime 2277 415' 2661' 15* 65 28* 133’ 95' Dolomite 1145 265 b 1542 d 41 b 662 54' 478' 43* Ash 338 241*b 1073b 46 b 32 31* 135* 71 b Slag 1268 263b 1295' 66' 342 43 b 226b 67b Fine sand No liming 278* 1705* 26* 98* Lime 2467 432' 3737' 11* 73 24’ 115b 79' Dolomite 1240 321 b 2390 d 41 b 717 55b 492 b 41* Ash 367 310b 1880b 43 b 35 27* 106*b 7bu Slag 1373 326b 2152' 64' 370 37*b 208' 67b Table 7. The pH(CaCl2), ECEC (me/kg soil) and 1 M KCI extractable (Al+H) content (me/kg soil) of the soils without liming and with four liming agents at the end of the pot experiment. Muddy fine sand Fine sand pH(CaCl2 ) ECEC (Al+H) pH(CaCl 2) ECEC (Al+H) me/kg soil me/kg soil No liming 4.3a 71“ 18.0C 4.6* 98“ 12.5' Lime 6.6' 128 d 1.7* 6.1' 170' 2.7* Dolomite 6.1 d 111' 2.8“ 5.7* 148d 3.5b Ash 4.7b 71* 12.0bc 4.8 b 103 b 8.8 d Slag 5.3' 88b 5.0*b 5.2' 119' 4.9' Discussion In slag the Ca content, indicating the amount of acid neutralized, was about 79 % of the content in line and about 84 % of the content in dolomite. In both the incubation and pot experiments the increases in pH(CaC 2 ) obtained with slag were lower than expected on the basis of the laboratory analysis. The content of Ca + I.6sxMg soluble in 1 M HCI did not give a better estimate for the neutralizing capacity of slag. The methods applied in Finland to carbonatic limestones, when applied to slag, would appear to lead 380 to an overestimation of its properties. The amount of Ca soluble in 1 M HCI may be a better indicator than the amount of Ca 4- I.6sxMg or the amount of acid neutralized, though not a good one. Certainly the properties of slag as liming agent should be determined by other methods than are the properties of carbonatic limestones. TORSTENSON and ALVELID (1952) have proposed the use of 0.1 M or 0.05 M HCI. After an experimental period of 16 months about 65 % of the 1 M HCI soluble Ca or Mg added in slag was neither in the yields nor in exchangeable form in the soils. The corresponding figure for lime was about 15 % and for dolomite about 35 %. The release of Ca and Mg from slag was very slow in both the pot and incubation experiments and it may be even slower in the field. If we assume that the decomposition of slag will continue in the soil at the rate observed in the pot experiment, the whole amount of added slag (24 g/ pot) may be decomposed after 40 months. However, NAUMANN (1939) founf that in the soil a colloidal layer of silicic acid, amorphous oxides and hydroxides forms on the surface of the slag particles, causing the decomposi- tion of slag to become slower and slower. Therefore the long-term effect of slag in the soil may fall short of expectation. For this study the slag was ground to a fineness such that 98 % passed through 1-mm sieve, and the main fraction 0.125-0.250 mm comprised 51 %. In Finland the regulation is applied that 50 % of limestone should pass through 0.15-mm sieve and 98 % a 2-mm sieve. The fraction below 0.3 mm may comprise 70 % (JAAKKOLA and 1980). The slag of this study was ground near the same fineness than the two limestones. KAPPEN (1933), BUCHER (1951) and CHICHILO et al. (1954) studied slag and lime both ground to the same fineness. They observed slag to neutralize the soil acidity to a lesser degree than lime, when the amounts of agent added were such as to have equal neutralizing ability. JAAKKOLA (1979) in Finland obtained in field and pot experiments equivalent results to these. So far as the neutralizing ability of slag is concerned, our results are in good agreement as well. The amount of slag recommeded for agriculture should be at least threefold the amount of lime required, if equal increases in pH(CaCl2 ) are to be obtained. The proportion of non-exchangeable Ca and Mg of that applied in slag was alike for both nutrients, revealing that there were no differences in the release of Ca and Mg from the fine ground slag. The ability of ash to neutralize the soil was low. At the same time turnip rape was able to take up a greater percentage of the Ca applied in ash than of Ca applied in slag. The availability of Mg in ash for turnip rape was considered non-existent and the proportion of non-exchangeable Mg in the soil remained high. In this study the exchangeable Mg content of the soils gave no evidence of the fixation of Mg to non-exchangeable form when lime was used. In earlier studies (e.g. KAILA 1974, JOKINEN 1981, JOKINEN 1982) such was observed. However, in comparison with the unlimed control the decreased Mg content and Mg uptake by turnip rape and 0.01 M CaCl2 extractable Mg content of 381 the soils indicated that the available Mg resources in the soil for this plant were indeed reduced, even though the lime contained Mg. Acknowledgements: The financial support received from theFoundation for Research of Kemira Oy is gratefully acknowledged. Rautaruukki Oy provided the basic slag and the City of Kuopio (Haapaniemi Power Plant) the peat ash for this study. References BROWN, G. G. & THATCER; K. F. J. 1967. The production and properties of basic slag. Proc. Fert. Soc. 96: 1-47. BUCHER, R. 1951. Die Wirkung von grobem und feinem Hiittenkalk (Hochofenschlacke) auf Boden und Pflanzenertrag. Z. Pflanzenern. Diing. Bodenk. 53; 121-143. CHICHILO, P. P., ARMIGER, W. H., SPECHT, A. W. & WHITTAKER, C. W. 1954. Plant nutrients from slag. Furnace slag as a source of plant nutrients and its effectiveness relative to limestone. J. Agric. Food Chem. 2: 458-462. JAAKKOLA, A. 1979. Kalkkikivijauheen, dolomiittikalkin ja masuunikuonan vertailu. MTTK, Maanvil- jelyskemian ja -fysiikan laitos Tiedote 10: 1-17. & JOKINEN, R. 1980. Comparison of fine and coarse limestones in pot and field experiments. Ann. Agric. Fenn. 19; 108—124. JOKINEN, R. 1981. Soil magnesium and fertilizer magnesium uptake by ryegrass on nine mineral soils at two ammonium nitrate levels 11. Magnesium content of soils. Ann. Agric. Fenn. 20; 244-252. 1981. Effect of liming on the magnesium status of some mineral soils and the fate of fertilizer magnesium. J. Scient. Agric. Soc. Finl. 53: 126-137. 1982. Effect of liming on the value of magnesium sulphate and two dolomitic limestones as magnesium sources for ryegrass. J. Scient. Agric. Soc. Finl. 54: 77-88. KAILA, A. 1971. Effective cation-exchange capasity in Finnish soils. J. Scient, Agric. Soc. Finl. 43; 178-186. 1974. Effect of liming on basic exchangeable cations of soil.]. Scient. Agric. Soc. Finl. 46: 167-174. KAPPEN, H. 1933. Die landwirtschaftliche Verwendbarkeit der Hochofenschlacken. Arch. Pflanzenbau 10; 87-128. NAUMANN, G. 1939. Über die Zersetzung von Eisenhochofenschlancken. Bodenk. Pflanzenern. 15; 74-126. NORRMAN, G. 1978. Slagger som kalkningsmedel. Nord. Jordbr.forskn. 60: 710-711. SCHARRER, K. & MUNK, H. 1956. Zur Methodik der nassen Veraschung in der agrikulturchemischen Analyse. Agrochimica 1: 44-55. STEEL, R. G. D. & TORRIE, J, H, 1960. Principles and procedures of statistics. 481 p. New York. TORSTENSSON, G. & ALVELID, D. S. 1952. Om användning av masungnslagg som kalkningsmedel i jordbruket. Rung. Lantbr.akad. Tidsskrift 91: 57-75. Ms received November 5, 1982. 382 SELOSTUS Dolomiittikalkki, masuunikuona ja turpeen tuhka kalkitusaineina sekä kevätrypsin kalsiumin ja magnesiumin lähteinä Raili Jokinen Helsingin ylioppisto, Maanviljelyskemian laitos, 00710 Helsinki 71 Dolomiittikalkin, masuunikuonan ja turpeen tuhkan arvoa maan happamuutta neut- raloivana aineena verrattiin kalkkikivijauheeseen sekä eri kalkitusaineiden vaikutusta maan vaihtuvan (pH 7) kalsiumin, magnesiumin ja kaliumin pitoisuuteen tutkittiin muhitus- ja astiakokeissa. Kevätrypsin (Brassica campestris v. oleifera f. annua; lajike Candle) kykyä käyttää hyväkseen eri kalkitusaineissa tulevaa kalsiumia ja magnesiumia selviteltiin as- tiakokeessa. Kalkkikivijauhe ja dolomiittikalkki 2 olivat normaaleja kaupan olevia tuotteita. Turpeen tuhka saatiin Kuopion kaupungin Haapaniemen voimalasta. Tämän ns. arinatuhkan hiek- kapitoisuus oli korkea. Rautaruukki Oy:stä saatu masuunikuona oli jäähdytetty vedellä ja jauhettu niin, että 98 % läpäisi 1 mm seulan. Laboratoriossa määritettiin 1) kalkitusaineiden neutraloiman hapon määrä (milliekvivalentteina), joka kalsiumiksi muun- nettuna ilmoittaa ekvivalenttisen kalsiumpitoisuuden (Ca, %) 2) 1 M HCI liukenevan kalsiumin määrä (Ca, %) 3) 1 M HCI liukenevan kalsiumin ja magnesiumin määrät, joiden perusteella laskettiin kaavan Ca + l,6sxMg mukainen kalkitusaineiden neutraloiva kyky (%) Kalkitusaineiden ominaisuudet on esitetty taulukossa 2. Tutkimuksen kokeet toteutettiin kahdella happamalla maalla, liejuisella hienolla hiedalla ja karkealla hiedalla; kummankin pH(CaCl 2 ) 4,8. Muhituskokeessa 390 grammaan liejuista hienoa hietaa tai 360 g karkeaa hietaa lisättiin 0,6 g, 1,2 g tai 2,4 g kalkkikivijauhetta, 2,4 g dolomiittikalkkia, 2,4 g turpeen tuhkaa tai 2,4 g masuunikuonaa sekä 1/10 astiakokeeseen annettujen ravinteiden (N, P, K, B, Cu, Mn, Zn, Mo) määrästä. Kalkitsemattomiin verran- nemaihin lisättiin vain ravinteet. Maiden kosteus pidettiin 25 % ilmakuivan maan painosta koko muhituksen ajan (16 kuukautta). Kasvukausien aikana astiat olivat ulkona, mutta valolta suojattuina ja talvella +5 °C vakiolämpötilassa. Kaksi kasvukautta jatkunutta astiakoetta varten punnittiin Mitscherlich-astioihin 3,9 kg liejuista hienoa hietaa tai 3,6 kg karkeaa hietaa ja maihin sekoitettiin 24 g kalkkikivijauhetta, dolomiittikalkkia, turpeen tuhkaa tai masuunikuonaa. Kokeeseen kuului myös kalkistemat- tomat verranne astiat kumpaakin maata. Välittömästi kalkituksen jälkeen maihin lisättiin ravinteita astiakokeisiin riittäviksi osoittautuneet määrät. Kevätrypsi kylvettiin aluksi tiheäksi kasvustoksi ja harvennettiin taimelle tulon jälkeen yhdeksäksi yksilöksi. Sato korjattiin kukintavaiheessa. Kalkitusaineiden maan happamuutta neutraloivaa kykyä verrattiinpH(CaCl 2):n, efektiivi- sen kationinvaihtokapasiteetin ja 1 M KCI uuttuvan (Al+H) pitoisuuden perusteella. Muhituskokeessa 2,4 g dolomiittikalkkia, turpeen tuhkaa tai masuunikuonaa olivat saman arvoisia kuin vastaavasti 1,7 g, 0,4 g tai 0,8 g kalkkikivijauhetta. Samalla määrällä (2,4 g) eri kalkitusaineita saadut pH(CaCl 2 )-luvun muutokset kalkitsemattomaan verrattuna olivat lie- juisessa hienossa hiedassa ja karkeassa hiedassa seuraavat: Kalkki- Dolomiitti- Turpeen Masuuni- kivijauhe kalkki tuhka kuona IjHHT 2,0 1,5 0,3 0,8 KHt 1,4 1,1 0,2 0,6 383 Mikäli eri kalkitusaineilla halutaan saada yhtä suuri pH(CaCl 2 );n muutos, dolomiittikalkkia tulisi käyttää noin 1,4 kertaa, turpeen tuhkaa noin 7 kertaa ja masuunikuonaa noin 3 kertaa niin suuri määrä kuin kalkkikivijauhetta. Astiakokeessa kevätrypsin sadot sisälsivät vain muutamia prosentteja kalkitusaineina lisätystä kal- siumista tai magnesiumista. Satojen ottaman ja maassa kokeen lopussa vaihtuvana (pH 7) olevan ravinnemäärän summa osoittaa näillä menetelmillä analysoitavissa olleita kalsiumin määriä. Kun kal- kitusaineiden mukana maahan lisätyistä ravinnemääristä vähennetään analyyseissä löydetyt määrät, jään- nös osoittaa uuttumattomaksi maahan jääneitä määriä. Kalkkikivijauheen sisältämästä kalsiumista oli uuttumattomana keskimäärin 13 %, dolomiittikalkin kalsiumista 41 %, turpeen tuhkan 45 % ja masuunikuonan 65 %. Lisätystä magnesiumista oli uuttumattomana 42 % dolomiittikalkilla, 74 % turpeen tuhkalla ja 67 % masuunikuonalla käsitellyissä maissa. Kalkkikivijauheiden ja dolomiittikalkkien neutraloivaa kykyä osoittavien menetelmien käyttö masuunikuonan ominaisuuksien analysoimiseen antaa masuunikuonasta liian edullisen kuvan. Sen vuoksi masuunikuonan arvo kalkitusaineena tulisi osoittaa jollakin muulla paremmin tarkoitukseen sopivalla menetelmällä.