TREATMENT OF STABLE MANURES -j^| 



carbonate of lime, and is not worth the cost of hauling any distance. 

 It can not take the place of burned limestone. 



Gypsum. Gypsum, or land plaster (sulphate of lime), occurs 

 in considerable quantities in this State and Nevada, and is now 

 being mined and ground at a low price in the San Joaquin Valley. 

 It acts directly in correcting soils made alkaline by presence of 

 carbonate of soda. Applied to soils not alkaline, gypsum sets free 

 potash, magnesia, and ammonia, which may be present in insoluble 

 form; and it also causes potash to be transferred from the upper 

 to the lower layers of the soil, so that roots can everywhere find 

 a store of it. Hence its special value when applied to deep-rooting 

 plants. The reason why gypsum is so capricious in its action, 

 which was long a mystery, is now held to be clear, because upon 

 soils that are tolerably rich in fixed potash it will do good service, 

 while upon soils poor in potash it will not. In any event gypsum 

 is to be regarded as an excitant rather than as a form of plant food. 



Of the several uses of gypsum, probably its chief value lies in 

 its power as an absorbent. If added to manure in excess it delays 

 fermentation, and it is, therefore, not a desirable addition to the 

 compost heap. But for covering fermenting manures or scattering 

 around moist places in horse and cow stables to absorb odors and 

 fix volatile manurial substances it is of value. 



Marls. Marl is a calcareous earth, and is called shell marl, 

 rock marl, earthy marls, etc., according to its origin and mechanical 

 condition. A number of samples from different parts of the State 

 have been analyzed by Professor Hilgard and some of them com- 

 mended for local application to soils needing lime, but not valuable 

 enough to warrant hauling far. Marl which sometimes occurs 

 in California too near the surface is injurious to trees, causing 

 yellow leaf and die back when reached by the roots. 



BARN-YARD MANURE AND COMPOST 



Where fruit growing is carried on with stock growing, there 

 are abundant supplies of manure available, but this combination 

 is not characteristic of California, though prevailing to some extent, 

 and likely to be more prevalent as fruit planting extends farther 

 from the centers which are wholly given to it. But even in the 

 fruit centers there are certain amounts of material available from 

 the animals that are kept for cultivation and hauling, or to be had, 

 often, for the expense of hauling from adjacent towns. 



As already stated, coarse, unrotted manure can seldom be used 

 to advantage in this State, unless it be in heavy soils in regions 

 of ample rainfall, or on lighter soils, perhaps, if well irrigated; 

 and even in such situations either finely divided or well-rotted 

 manure is infinitely superior. Corral scrapings, which are usually 



