392 ANNUAL REPORT OF THE Off. Doc. 



The following is a sample of the field excui'sions : 

 10 (3) Field Lesson. Relation of crops to types of soil, plant roots, 

 nodules on legumes. Materials. Rule, spade. 



(a) Go across several farms. Notice what kinds of crops are being 

 grown on sandy soils, on clay soils on wet land. Some crops can 

 be raised on a great variety of soils. Thus, timothy hay can be 

 grown successfully on clays, clay loams, and loams, or even on fine 

 sand, but it usually does best on the clay or clay loams. Peaches 

 usually thrive best on fine, sandy soils. White or Irish potatoes 

 require a loose, moist soil for their best development. To what ex- 

 tent are the crops varied with the kinds of soil in your region? 



(b) Dig down beside a cornstalk; notice how deep it is to the 

 first roots; to the deepest roots. Repeat in several places and on 

 different kinds of soil, if possible. How deep could a cultivator go 

 without hurting the roots? Similarly, find the depth and lateral 

 extent of roots of clover and other crops. As the roots decay they 

 add to the humus and make the soil more productive. What plant 

 roots examined would tend to deepen the soil and be most valuable 

 as they decay? 



(c) Carefully dig up a clover plant; look for nodules on the roots. 

 Bacteria live in these nodules. By means of these nitrogen is taken 

 from the air in the soil and is made available for plant use. Nitro- 

 gen is one of the most important foods for plants. It is the most 

 expensive part of common fertilizers. Only members of the pea 

 family (legumes) are capable of thus getting nitrogen. Why does 

 clover benefit a crop that follows it? Consider the depth and 

 amount of roots as well as the nodules. Dig any of the following 

 or other legumes that you see and look for nodules: White clover, 

 sweet clover, beans, peas, vetches, alfalfa, etc. Later lessons will 

 consider this topic again. (Farmers' Bui. 215, p. 15; Experiments 

 with Plants pp. 133-135 and 149; Physics of Agriculture, pp. 150- 

 157.) 



Tlien follows two recitations covering this subject. 



Next a laboratory exercise is selected for illustration which reads 

 as follows: 



GO (a) Laboratory. Study of the spike of wheat. 



Materials. Heads of two or more varieties of wheat. The fol- 

 lowing are suggested: Dawson's Golden Chaff, a soft white winter; 

 Fultz, a red winter; Turkey, a hard winter; Fife, or blue stem, a 

 hard spring; Durum, a macaroni. The spikes of wheat should be 

 laid between pieces of moistened blotting paper for several hours 

 before handing to students, in order to toughen the parts. 



Request each student to report the following, after examining 

 a head of wheat: 



1. Number of spikelets in the spike of wheat. 



2. Number of flowers in each spikelet. 



3. Number of grains in the whole spike. 



4. Determine the number and arrange weight of grains occupying first, 

 second, third and fourth place from rachis. 



5. Number of empty glumes in a spikelet. 



6. Make a sketch of the beak, shoulder, and. auricle of the empty glume. 



7. How does the flowering glume differ from the palea? 



