FIFTH ANNUAL YEAR BOOK — PART VI. 499 



From forty to fifty years ago all of the soils in Iowa were remarkably 

 porous and they absorbed rain water rapidly. They contained large quan- 

 tities of humus (decomposing vegetable matter) which attracted and held 

 water like a sponge. From thirty to forty years ago atmospheric air entered 

 into and circulated freely through the new prairie soils, and large quantities 

 of moisture were condensed in them. But their condition now is very dif- 

 ferent from their condition then. Many crops of wheat, oats, timothy, etc. . 

 have destroyed most of the humus which they contained formerly, and 

 instead of being porous and moist in dry weather they have become com- 

 pact and dry. The inorganic food materials required by growing plants 

 consist of nitrogen, potash, phosphorus, lime, sulphur, soda, chlorine, iron, 

 manganese and magnesia. They are found in soils united as compounds, 

 but they can not be used by trees and herbaceous plants until they have been 

 dissolved by water, carbonic acid, oxygen, etc. The rainfall during the 

 last forty years was sufficient to enable us to grow good crops of wheat, 

 oats, etc. , but we used it carelessly and extravagantly and the results were 

 that we have had many poor crops and have low water levels now. How 

 can we save enough of the rain which falls on our fields and orchards? is an 

 important question which is not hard to answer. 



The results of experiments, which were conducted by competent men, 

 proved that remarkably large quantides of water are exhaled by many kinds 

 of plants and the soils on which they are grown. Laws of England and 

 Hellrigal of Germany have shown (after many careful trials) that the cereals, 

 grasses and other kinds of plants, have exhaled water during their periods 

 of growth to the amount of two hundred to three hundred times the weight 

 of the dry matter in them when they were fully grown. They report also 

 that an acre of wheat exhaled 400,000 pounds of water during its period of 

 growth. The cereals, blue grass, timothy and other plants, which obtain 

 their food through surface roots, cause a much greater loss of water from 

 soils than red clover, corn and other plants which extend many of their roots 

 to greater depths. To grow large crops we must have porous soils, which 

 are well supplied with humus. The air circulates freely through such soils, 

 and frequently during July, August and September more atmospheric 

 moisture is condensed in them than fall from the clouds in the form of rain. 

 The great value of humus in soils is shown by the results of an experiment 

 reported by Dr. Stephen Hales, to wit: Equal weights of coarse sand, fine 

 sand, ordinary clay soil, loamy soil and humus were placed in a damp cellar 

 for twenty-four hours, when it was found that each of them had absorbed 

 the following fractional weights of water, viz: Coarse sand, y§(); fine sand, 

 3-100; ordinary clay soil, j^q; loamy soil, jW; and humus, fVu of the 

 weight of each sample. When humus is decomposed in soils, carbonic acid 

 and other gasses are set free, which are necessary to render the different 

 kinds of plant food available for the use of plants. 



To restore the lost fertility of soils, proper tillage, stable manure and a 

 short rotation of crops are necessary. The first crop should be Manshiry 

 barley, or some other variety equally early and productive; the second crop 

 should be red clover and the third crop should be a good variety of corn. 

 The barley should be sown early in the spring on fall plowed fields. The 

 variety recommended is productive; it would be ready to harvest in the first 

 week of July, and it would require much less water from the soil than a 



