236 



Bulletin 247. 



Here there are eight plats treated precisely alike which varied in 

 moisture from 10.6 to 17.8 per cent, and in yield of green maize fodder 

 from 731 to looi lbs. The differences in the percentages of moisture 

 in these plats are due to the character and perhaps the topography of 

 the soil, the lower percentages being on the sandier and higher ground. 

 In general the lower the percentage of moisture the larger the yield of 

 maize. It is extremely unfortunate that the proportion of water-soluble 

 nitrogen was not determined on each of these plats. 



It is well known that sandy soils will not retain as much water as 

 those containing a higher percentage of clay, but that plants can avail 

 themselves of lower percentages of water in the sandy soil. The pur- 

 pose of giving this table is to show how careful one must be in inter- 

 preting the results of soil moisture determinations. Suppose one is mak- 

 ing a pot experiment using a made soil by mixing soil, sand and manure 

 as is customary, and he does not secure an equal mixture in the different 

 pots, what value would be the results of soil moisture determination? 



The following table gives the percentages of moisture and the yields 

 of maize and weeds from two plats which were cultivated in the ordinary 

 manner and two which received one cultivation on May 15, six days 

 after the maize was planted. One of these was allowed to grow up to 

 native seeds while the other was sown to millet on May 15. Plat 462N 

 will be explained hereafter: 



Table IX. — Effect of Cultivation and "Weeds." 



Water in soil, per cent 



Maize fodder, green substance, lb. 



per acre 



Millet or weeds, green substance, 



lb. per acre 



Total green substance, lb. per acre. 

 Maize stover, field cured lb. per 



acre 



Maize ears, lb. per acre 



Plat 461 

 cultiva- 

 tion. 



17 



23 



8 

 , 622 



23 , 622 



,410 

 ,914 



Plat 

 462 



millet. 



16.9 



2,139 



10,881 

 13,020 



775 

 16 



Plat 462N 



millet and 



weeds. 



6,834 



22 ,440 

 29,274 



816 

 612 



Plat 



463 



weeds. 



Plat 46a 



CUltiVa- ; 



tion. 



15-5 

 4,061 



10, 106 

 14,167 



1,364 

 62 



16.0 

 22 , 661 



22 , 661 



3.224 

 3,069 



This table shows that the growth of millet or weeds greatly checked 

 the growth of maize, the yield of green substance where the millet was 

 sown being only one-tenth and where weeds were allowed to grow only 

 one-fifth that produced under ordinary cultivation. Of course the stalks 

 on these weedy plats produced practically no ears and was, therefore, 

 virtually a failure. This table also shows that the total green product 



