238 



should also be taken into consideration that the more lime used, the less should 

 fertilizing with potassium be neglected. In using stable manure, it is well 

 to put the lime in the soil sometime before the manure is added. Bone meal 

 should be avoided on soils containing lime. In the same way, it is not ad- 

 visable to use ammonia and ammonia superphosphates together with lime. 

 Pulverized quick lime should be used on binding, clayey soils ; lump or slaked 

 lime on better loam soils. 



In regard to the need of lime by the different plants, Hoffmann states 

 that the Leguminoseae in general are distinguished as the most responsive 

 to apphcations of Ume, but that the Lupines and Serradella may be con- 

 sidered as hostile to lime and sweet peas also do not like the direct use of 

 lime or marl. 



In the use of marl also, the lime is the most active princii>lc and hence 

 it follows that a clayey soil, rich in humus, bears marling better than a poor 

 sandy soil which in turn can be more benefited by a clay marl than by a 

 lime or sand marl. The sometimes dreaded "impoverishment" from the use 

 of marl will take place only if fertilizing with stable manure is delayed. The 

 last is indispensable for all soils and especially for heavy ones in keeping the 

 fields productive. No mineral fertilizer can replace stable manure. 



The influence exerted by the lime contained in marl upon decomposition 

 of the humus substances is illustrated very clearly by Petersen's^ experi- 

 ments. He determined the amount of carbon dioxid produced in different 

 soils by the process of decomposition with and without the addition of cal- 

 cium carbonate. In using a heavy clay soil, known to be perfectly sterile, 

 with 1.98 per cent, humus and 36 per cent, of its water holding capacity in 

 water content, he obtained in 16 days 0.07 per cent, of the weight of the dry 

 soil in carbon dioxid. On the other hand, the same soil under the same con- 

 ditions with the addition of Yj per cent, of calcium carbonate, mixed in the 

 clay as marl, yielded 0.20 per cent, carbon dioxid, or per liter of dry soil, 

 without addition of lime, 0.9153 g. ; per liter of dry soil, with addition of ^^ 

 per cent, lime, 2.6167 g. 



A leaf mould with strongly acid reaction consisting of 58 per cent, 

 humus and 30 per cent, of the absorptive capacity in temporary water con- 

 tent, yielded after 16 days, without and with the addition of t per cent, cal- 

 cium carbonate (when the earth still gave an acid reaction) : per liter of dry 

 soil, without the lime addition, 0.891 1 g. CO2 ; per liter of dry soil, with the 

 addition of i per cent, calcium carbonate, 3.386 g. CO.. 



With the addition of 3 per cent, calcium carbonate, the soil yielded 

 5.3476 g. carbon dioxid, while the series of check experiments, free from 

 lime, produced only 0.9664 g. CO.. The addition of the lime, therefore, had 

 caused 3 to 4 times as great a production of carbon dioxid, i. e., humus de- 

 composition, as in the soil in an unmarled condition. 



Heiden, in Pommritz, summarizes thus the effect from the use of marl : 

 The chemical action arises primarily from its content of calcium carbonate 



1 Jahresbericht f. Agrik. 1870-72. Landwirtsch. Ver.suchsstationen, Vol. 13, p. 155. 



