Proceedings of Seventeenth JSTobmal Institute; 100 



as an average of five years. The benefit comes from securing 

 cool, moist conditions under the mulch. 



Some field experiments. (Me. 236.) In a one-year test, which 

 will be repeated, nitrate of soda was found superior to sulphate 

 of ammonia as a potato fertilizer, the difference being about 6 per 

 cent. Contrary to an unintended experiment in 1913, sulphate 

 of iron was found harmful to potatoes when sprayed on the tops 

 in 1914; so it is regarded as unsafe to use this material to kill 

 mustard in potato fields. 



On moderately heavy loam, underlain with an almost impene- 

 trable subsoil, dynamiting proved of no benefit as a soil prepara* 

 tion either for oats or for apple trees. 



Fertility and iveeds. (IST. Dak. 112.) Samples of many weeds 

 were collected and analyzed, and the data arranged in most 

 interesting tables to show the draft of these weeds on soil fer- 

 tility, and their effect on the yields of the crops infested. A ton 

 of lambs' quarters would remove from the soil nearly 19% pounds 

 of nitrogen, but a ton of marsh elder (kinghead) would take only 

 3 pounds, while giant ragweed, ragweed, wild oats, rough pig- 

 weed, barnyard grass, purslane and pigeon grass come between 

 in two groups, the first four removing more than 10 pounds of 

 nitrogen per ton, the others distinctly less than that amount. Of 

 phosphoric acid the giant ragweed removes most, 51/^ pounds per 

 ton, and marsh elder least. 



The author figures that a ton of either lambs' quarters or giant 

 ragweed would remove enough fertility to grow 5 bushels of 

 wheat, a ton of rough pigweed or barnyard grass enough for 

 ■4 bushels, a ton of pigeon grass for 3 bushels and a ton of marsh 

 elder enough for 2 bushels of wheat. 



ANIMAL INDUSTRY 



Maintenance requirement of cattle. (Mo. Research, 18.) The 

 data and conclusions given in this bulletin rest on work continued 

 for seven years, probably the most comprehensive studies ever 

 made of the development, growth, feeding, metabolism and com- 

 position of the tissues of cattle. 



