SOILS FERTILIZERS. 213 



" The results of tests of many samples from the five large soil areas in Iowa 

 show that soils in the Mississippi loess, the southern Iowa loess, and the lowan 

 drift areas are very apt to be acid while those in the Wisconsin drift are only 

 occasionally in need of lime and those in the Missouri loess are very rarely in 

 an acid condition. 



" The average amounts of limestone needed by acid soils in the large areas 

 have been calculated and average recommendations have been made. When 

 soils within the Missouri loess and Wisconsin drift areas show acidity an appli- 

 cation of 3i to 4 tons of limestone per acre may be regarded as the proper 

 amount to use in most cases. Three and one-half to 44 tons of limestone per 

 acre is the average recommendation for the Mississippi loess, 34 to 5 tons per 

 acre for the southern Iowa loess, and 4 to 5^ tons per acre for the lowan drift. 



"Acid soils in these three latter areas are usually underlaid by acid sub- 

 surface soils and subsoils, and as the limestone requirement is determined only 

 for the surface soil future tests of the soils will be necessary to insure the 

 maintenance of a basic reaction, even after the application now recommended 

 is made. 



"After acidity in the soil has once been entirely neutralized the use of 1 to 2 

 tons of limestone per acre once in four or five years should prove ample to 

 keep the soil from becoming acid." 



The comparative tests of methods for detecting soil acidity indicated that 

 the A'eitch and litmus paper methods are very satisfactory when made by 

 experienced persons. The litmus paper test is especially recommended for field 

 use. 



Ground limestone or limestone screenings are considered the cheapest and 

 best form of lime to use on Iowa soils, being fully as satisfactory as hydrated 

 or caustic lime and not subject to the objection of causing injurious effects in 

 the soil. The limestone can be more cheaply secured in the State than the 

 other forms. 



The utilization of muck lands, C. S. Robinson (Michigan Sta. Bid. 273 

 (1914), PP- 3-29, figs. 8). — This is a general discussion of types, agricultural 

 uses, crop adaptations, and fertilizer requirements of muck lands, based in 

 part upon work done by the Michigan Station and in part upon other investi- 

 gations. 



Swamp lands are said to constitute one-seventh of the total area of the State, 

 a large portion of which could be developed in a practical way for the per- 

 manent production of crops by draining and fertilization. " Potash and phos- 

 phoric acid are the mineral fertilizing elements which give the best returns, 

 while barnyard manure also causes a large crop increase in most cases. Except 

 on distinctly acid deposits, lime does not as a rule give good results. 



"[Muck] deposits which are not suited to the direct production of crops may 

 be used to reinforce manure either in composting or as a stable litter. In this 

 way the manurial value of the muck is increased while the valuable ingredients 

 of the mixture may be materially enhanced by the addition of phosphatic 

 material." 



Soil survey of Ralls County, Missouri, A. T. Sweet and W. I. Watkins 

 (U. S. Dept. Agr., Advance Sheets Field Operations Bur. Soils, 1913, pp. J^l, 

 fig. 1, map 1). — This survey, made in cooperation with the University of 

 Missouri, was issued November 24, 1914. It deals with an area of 307,840 acres 

 in northeastern Missouri which comprises three distinct topographic divisions, 

 the level or gently rolling uplands, the hilly regions, and the bottom lands or 

 stream flood plains. 



