714 IOWA DEPARTMENT OF AGRICULTURE 



Further information regarding the effects of lime, the losses from the 

 soil, the kind to use, the method of application, etc., may be found in 

 Circular No. 2, of the Iowa Agricultural Experiment Station. 



Carbonates. — Acid conditions cannot exist in a soil which contains an 

 abundance of carbonates. A test therefore of the presence of carbonates 

 will give indications of the acidity of the soil. This test is based on 

 the fact that acids attack carbonates with the liberation of carbon 

 dioxide gas. Thus when soils containing carbonates are treated with 

 hydrochloric acid there is a foaming or effervescence due to the rapid 

 evolution of the gas. Conversely, if a soil is treated with hydrochloric 

 acid and there is abundant foaming, evidence is at hand that carbonates 

 are present in considerable amounts and the soil cannot be acid. If no 

 foaming occurs then the soil may be acid or neutral. 



To make the test, a little concentrated hydrochloric acid is poured on 

 a small sample of moist soil in a clean dish or other receptacle. The 

 extent of foaming is a rough indication of the amount of carbonates 

 present in the soil. 



A small amount of hydrochloric acid is all that is necessary to make 

 a large number of tests and it may be easily secured at any drug store. 

 Care should be taken that the acid is not brought into contact with the 

 skin or clothing, as bad burns may result. If any of it is accidentally 

 spilled it should be washed off immediately. 



Even although negative reuslts are secured in the surface soil, tests 

 should be made of the subsoil as the presence of carbonates there would 

 be of considerable importance particularly in the case of deep-rooted 

 crops. 



Physical Conditions. — It is hardly necessary to emphasize the need of 

 proper methods of tillage and cultivation to keep the soil in proper 

 physical condition. Every farmer knows that he may conserve the 

 moisture in his soil during a dry season by keeping it cultivated. The 

 value of the proper preparation of the seed bed for all crops is also a 

 matter of common knowledge. Proper plowing and disking, the killing 

 of weeds, etc., are recognized as essential for satisfactory crop growth. 



If the soil is open and porous, dries out too rapidly and is deficient 

 in organic matter, as is often the case due to the "burning out" of this 

 important soil constituent, then applications of barnyard manure or 

 green manure should be made and lime applied. Not only is the physical 

 structure of the soil improved by such treatment, but satisfactory con- 

 ditions are offered for bacterial activity and there is consequently a 

 sufficient production of plant food to insure good crop growth. The 

 practice of green manuring to build up light soils cannot be too strongly 

 emphasized. 



Further information regarding green manure crops and methods of 

 green manuring may be found in Circular No. 10' of the Iowa Agricul- 

 tural Experiment Station. If the soil is heavy and cold and too much 

 moisture is apt to be present, applications of lime will help, and proper 

 drainage should be provided, preferably by the use of tile drains. 



Presence of Plant Food. — Tlj? presence of available plant food in the 

 necessary amount is one of the fhief requisites for the best growth of 



