WORK OF THE DELTA EXPERIMENT FARM IN 1912. 



9 



The results of various methods of tillage and green manuring and 

 the same methods with applications of potassium sulphate, potassium 

 chlorid, and superphosphate show some significant differences. The 

 most notable of these is the rather uniformly higher yields with 

 superphosphate under all conditions of tillage and the uniformly 

 better yields in proportion to stand wliich were obtamed by applying 

 the fertilizer in March over applying fertilizers at planting time. 

 Deep plowing showed better results than shallow, and green manure 

 gave generally better yields than were obtained from the bare fields. 



THE USE OF VARYING QUANTITIES OF SUPERPHOSPHATE. 



An expermient was conducted to determine the effect of applymg 

 superphosphate at different rates on land to wliich various tillage 

 methods were applied. Each of the eight plats used in the experi- 

 ment contained one-tenth of an acre 

 Table II. 



The results are given m 



Table II. — Jiesults obtained with potatoes on land treated with varying qnantities of 

 superphosphate at the Delta Experiment Farm in 1912. 



Treatnienl. 



Plowed 12 inches deep. 



Plowed 6 inches deep. 



Green manure. Bare. 



Green niannre. 



Bare. 



Superphosphate per acre pounds . . 



Stand per cent . . 



Wilt do.... 



Marketable yield per acre pounds . . 



Unmarketable: 



Undersized per cent. . 



Scabbv do 



600 



.34.7 



97.0 



8,805 



21.9 

 8.0 



1,200 

 34.0 

 81.0 



7,105 



15.3 

 2.4 



600 



31.7 



75.0 



10,402 



12.9 

 2.6 



1,200 

 38.7 

 50.0 



9,030 



20.9 

 4.5 



400 

 44.9 



84.0 

 8,575 



23.6 

 11.8 



800 



36. 3 



77.0 



8,105 



18.6 

 9.9 



400 



36. 3 



77.0 



9,360 



21.7 

 10.3 



800 



33. 6 



SCO 



8,555 



39.8 

 11.1 



It is seen from Table II that varying the rates of superphosphate 

 application resulted in no consistent differences in yield. The growth 

 of haulm, however, was noticeably increased by the heavier applica- 

 tion. 



ACIDULATION OF IRRIGATION WATER. ^ 



With a view to studymg the effect of acidulatmg the u-rigation 

 water on the growth of potatoes and more particularly on the action 

 of the scab organism, Oospora scabies, an experiment was conducted 

 on four tenth-acre plats in field F. Commercial sulphuric acid was 

 used. The method used consisted in the placmg of a plank 10 

 inches wide and 6 feet long in the ditch at the head of each plat, the 



1 This work was planned in accordance with suggest ions of Mr. Karl F. Kellerman, Physiologist in Charge 

 of the OfTice of Soil-Bacteriology and Plant-Nutritiou Investigation. 



91517°— Cir. 127—13 2 



