FIELD CROPS 471 



will grow good oats, but heavy, undrained clays are too wet and cold 

 for the best growth of the crop. More water is required to produce a 

 pound of dry matter in oats than in any other cereal, hence the ne- 

 cessity for growing this crop on land which naturally retains mois- 

 ture or which is well filled with humus. On account of their lia- 

 bility to lodge, oats should not be grown on very rich soil or on low, 

 undrained lands. Good drainage is essential also in the prevention 

 of injury from plant diseases. 



Fertilizers and Manures. The quantities of the three im- 

 portant fertilizing elements removed by a crop of grain vary some- 

 what in different portions of the country, as they depend on the yield 

 of the individual crop and the proportion of grain to straw. For 

 this reason no general estimate of the fertilizer removed by an acre 

 of oats can be given. According to experiments in South Dakota a 

 45-bushel crop of oats removed from the soil approximately 44 

 pounds of nitrogen,- 16 pounds of phosphoric acid, and 37 pounds of 

 potash. A 30-bushel crop of corn removed a little more phosphoric 

 acid and potash and about one-third more nitrogen than the oats, 

 while a 40-bushel crop of barley removed considerably more of all 

 three of these fertilizing elements. A 15-bushel crop of wheat re- 

 moved but 35 pounds of nitrogen, 9 pounds of phosphoric acid, and 

 15 pounds of potash. These figures show that nearly as much fer- 

 tility is required to produce a good crop of oats as of any other grain, 

 so mat the common practice of using the poorest land on the farm 

 for growing oats is not to be commended. While the oat crop is a 

 vigorous feeder and will do better on poor soils than will most other 

 grain crops, yet the judicious use of fertilizers or manure is usually 

 profitable. The fertilizer problem is made difficult, however, by the 

 fact that on rich soil oats make a rank growth, which often results 

 in lodging and in conditions favorable to rust and other diseases. 



Unless the soil is very low in fertility the direct application of 

 barnyard manure to the crop is seldom advisable. Much more sat- 

 isfactory results can usually be secured by applying the manure 

 previous to growing some other crop in the rotation, such as corn. 

 The oats will then get the benefit of a part of the manure and of 

 the added humus in the soil, with less danger that a rank growth 

 of straw will be made at the expense of grain production. On very 

 poor soil the application of a few loads of well-rotted manure some 

 time previous to sowing oats can be made to advantage. The ma- 

 nure should be applied as evenly as possible and should be well 

 worked into the soil. Under these conditions the use of a small 

 quantity of raw rock phosphate with the manure is usually advis- 

 able. 



Experiments show that phosphorus is usually the most im- 

 portant addition which can be made to the soil for the production of 

 oats, but small quantities of nitrogenous fertilizer can often be used 

 to advantage. The oat crop makes most of its growth early in the 

 season when the weather is cool and before much of the nitrogen in 

 the soil becomes available for plant food. For this reason the ap- 

 plication of a small quantity of nitrogen in a readily available form, 



