80 The Bulletin. 



row a lot of vegetation, are injured by the drought more than where we did 

 not have a cover crop. The reason is obvious : the water supply is broken ; 

 not the fault of the cover crop, however, but of the faulty manner in which 

 it was put in. Later we will explain the method of preventing this injury. 



Vegetation increases the water-holding capacity of soil. When it is thor- 

 oughly mixed with the surface soil it acts very much as a sponge and absorbs 

 the excess moisture in tl^e soil and holds it in reserve for the fiiture needs of 

 the plant instead of letting it escape out of the land by surface evaporation 

 and underdrains, as it would otherwise do. When we consider that it takes 

 about 300 pounds of water to develop one pound of dry matter in corn (stalk 

 and ears) we can see the necessity of plenty of water if we expect large yields. 



Then, too, the cover crop adds direct plant food. Every plant is nothing 

 more nor less than a combination of different plant foods, and when a plant 

 Is put back into the soil it decays and disintegrates into the original elements 

 or plant foods. Now. when we put this vegetation in the bottom of the fur- 

 row we place it where it will decay slowly; in fact, in some instances requir- 

 ing several years to become available as plant food. This is because the bac- 

 teria and other organisms, whose work it is to take this vegetation and put it 

 in an available form for the plant, cannot get to this vegetation readily. When 

 it is finally broken down by the few agents that can touch it from the topsoil. 

 it is down below the main feeding area of the plant roots, and. therefore, is 

 of little benefit to the plants. What we want. then, is to get this vegetation 

 thoroughly mixed with the surface soil so that the beneficial bacteria and 

 organisms throughout the soil can quickly put it in an available form. 



Indirectly, vegetation adds plant food to the soil by providing a feeding and 

 breeding ground for the beneficial bacteria and organisms in the soil. Just a 

 word about the bacteria and organisms in the soil. In all of our soils we 

 have two kinds of these organisms, the beneficial and the harmful. The 

 harmful ones cause the plant food that is originally in the soil to be so changed 

 that it is in an unavailable form or in a form which the plants cannot use. 

 In this way the harmful agents can so destroy the plant food in the soil that a 

 soil naturally fertile enough to produce good crops will become very unpro- 

 ductive. The beneficial organisms work in jiist the opposite way. These 

 put in an available form the plant food which is in the soil. Thus it is that 

 sometimes just by the application of a good supply of humus-forming material, 

 preferably a leguminous crop, we get unusually large crop returns from the 

 following crop. And again you can see the absolute necessity of having this 

 humus well mixed with the surface soil instead of in the bottom of the furrow. 



Mechanically, humus aids in improving the soil by being thoroughly mixed 

 in between the soil particles, in that in our clay soils it holds the soil par- 

 ticles apart and in our sandy soils it helps to hold the soil particles together. 

 In our clay soils the soil particles, which make up the soil, have a tendency 

 to run together, causing the soils to harden and cake, making it very difficult 

 to break them up and to keep the soil in a fine, loose condition. But with 

 plenty of humus in the soil these particles are held apart and the land is more 

 open and porous. It is much easier tilled and the soil agents can improve the 

 soil more effectively. And again in the sandy soils this humus tends to hold 

 the loose particles together more compactly and prevents them from losing 

 so much fertility from leaching, and also gets the land in a much better tilla- 

 ble condition and a condition that helps the beneficial soil agents to get in 

 their work. You see, again, the necessity of having the vegetation well mixed 

 with the surface soil and not iu the bottom of the furrow where many farmers 

 have been putting it. 



How are we going to get the vegetation mixed with the soil? The chief 

 reason the farmer gives for putting this vegetation in the bottom of the fur- 

 row is to get it out of the way of future cultivation. But it is possible to get 

 this result without the disastrous results that have often followed the common 

 practice of turning under the crop. 



The first thing to do with land that has grown a cover crop, whether the 

 crop was used for hay or not, is to get on it with a disk or cut-away harrow 

 and to thoroughly cut to pieces the upper two or three inches of surface soil. 



