LEGUMES AND GRASSES 



33 



Legumes and grasses are well 

 suited to the cropping systems for 

 sandy farm lands of northeastern 

 Nebraska. Soil conservation prob- 

 lems in this section consist chiefly of 

 (1) preventing wind and water 

 erosion and (2) increasing crop 

 yields through improved so3 fertil- 

 ity. Legumes and grasses provide 

 maximum protection from wind 

 erosion. Lime and phosphate are 

 required on most land for sweet- 

 clover, lespedeza, and alfalfa. 

 Fertilizer nitrogen may be needed to 

 supplement the legume nitrogen 

 on most farms. 



At Lincoln, alfalfa used soil 

 moisture to a depth of 33 feet. 

 Deep subsoil moisture reserves were 

 not replenished during subsequent 

 cropping to small grains. Con- 

 tinuous corn restored some of the 

 subsoil moisture. Five years of 

 continuous fallow restored subsoil 

 moisture to field capacity to only 

 11 feet. Storage efficiency was 

 extremely low. 



At Lincoln, sweetclover and red 

 clover did not deplete soil moisture 

 reserves below 6 feet during 1928- 

 32. 



Crop-rotation experiments at 

 Lincoln showed that alfalfa, red 

 clover, and sweetclover were effec- 

 tive in increasing yields of corn and 

 small grain. Limited data showed 

 that sweetclover, in a 6-year rota- 

 tion without lime, did not supply 

 adequate nitrogen for the rotation. 

 These data indicate that nitrogen 

 fertilizer may be used in place of or 

 at least to supplement legume 

 nitrogen to maintain and increase 

 grain yields. 



Perennial grasses increased nitro- 

 gen and organic-matter contents 

 of the soil after 6 to 10 years at 

 both North Platte and Lincoln. At 

 North Platte, the rate of water 

 entry into soil increased with age 

 of grass. 



At Lincoln, side-oats grama, blue 

 grama, bluegrass, and bromegrass 



imparted the greatest stability to 

 soil aggregates,^ as measured by 

 the precentage of aggregates greater 

 than 0.25 mm. diameter. Two 

 years after the grass plots were 

 plowed and cropped, water-stable 

 aggregates in all grass plots except 

 buffalograss plots had decreased 70 

 percent. Buffalograss plots showed 

 approximately 50 percent decrease 

 in aggregation. 



Ka 



nsas 



Yields 



Green-manure experiments were 

 started at Hays, Kans., in 1908 7 

 and Colby, Kans., in 1915 (44). 

 Yields of several crops after green- 

 manure fallow, continuous cropping, 

 and ordinary fallow are presented 

 (table 25). 



In 1945, Hallsted 7 tabulated the 

 yields from the dryland experiments 

 at Hays. Annual precipitation 

 averaged 22.7 inches. 



His data indicate that yields of 

 winter wheat and barley after 

 green-manure fallow were less than 

 after ordinary fallow. Yields after 

 rye or pea green-manure fallow 

 were greater than with continuous 

 cropping. 



Kuska and Mathews (44) re- 

 ported the results of experiments 

 with crop rotations at Colby for 

 1915-50. Annual precipitation av- 

 eraged 18.5 inches. Their data on 

 yields of milo and winter wheat 

 in green-manure and comparable 

 rotations for 1915-47 are presented 

 (table 26). 



Their findings show that yields 

 of milo immediately after green- 

 manure fallow were lower than those 

 after ordinary fallow (table 26). 

 They concluded that this was be- 

 cause of moisture used in producing 



7 Hallsted, A. L. tabulated yields 



FROM DRYLAND AGRICULTURE TILLAGE 

 AND ROTATION EXPERIMENTS CONDUCTED 

 AT HAYS, KANSAS. KanS. AgT. Expt. 



Sta. [Unpublished Rpt.]. 1945. 



