KHODE ISLAND. 193 



with reference to active immunity in rabbits. Part of the results of 

 this work was published in Bulletins 144 and 146 of the station. 



The lines of work carried on under the Hatch fund by the depart- 

 ment of agronomy included a study of crop rotations to ascertain 

 the most economical methods of fertilizing and cropping Rhode 

 Island soils when but little stable manure is available. A study was 

 made of 3, 4, 5, 6, and 7 year crop rotations in this connection and the 

 efficiency of each in the improvement of the soil was observed. In 

 addition to this work observations were made on a market-garden 

 rotation, an experiment was conducted in continuous corn culture, 

 and attention was given to problems in grass, alfalfa, and com cul- 

 ture and the use of different phosphates. The results of the con- 

 tinuous corn-culture experiments indicated the value of sowing crim- 

 son clover at the last cultivation of corn as compared with the use of 

 winter rye in this connection. The experiments in grass culture were 

 continued mainly to determine the best top dressing for grass land 

 when chemical fertilizers only are available. The availability and 

 the residual effect of phosphoric acid applied in the forms of double 

 phosphate, raw iron and aluminum phosphate, roasted iron and 

 aluminum phosphate, floats, basic slag meal, fine-ground bone, acid 

 phosphate, dissolved bone, and dissolved bone black were compared. 

 In the selection and breeding of sweet com further comparisons were 

 made of the sweet corn which had been under selection for several 

 years and of commercial strains of the same variety. Work on 

 methods of planting com consisted of planting 2, 3, 4, 5, and G corn 

 kernels in the hill in comparison with the same number of kernels 

 planted equidistant in drills. The use of fertilizers in the different 

 rotations mentioned above was studied to ascertain the greatest possi- 

 bilities of profit rather than the greatest possible crops. Successful 

 tests of soil inoculation and of alfalfa seedings are reported. Fer- 

 tilizer experiments with grasses for lawn purposes showed that sheep 

 fescues and Rhode Island bent grasses persist where acid fertilizers 

 are used, but that Kentucky blue grass disappears under these condi- 

 tions, while it remains the prominent grass when alkaline fertilizers 

 are employed. Experiments in the artificial growing of the swamp 

 blueberry were continued in cooperation with this department, and 

 tests were made in spraying cucumbers and cantaloups with a view 

 to controlling a bacterial disease attacking these plants. 



The chemist made a study of the availability of the nitrogen in 

 certain materials used for fertilizing purposes, of the phosphoms 

 and potassium requirements of plants at different stages of growth, 

 the influence of crops on each other when supplied with deficient and 

 optimum amounts of nitrogen, nitrogen-gathering value of legimii- 

 nous plants, the relative growth of different kinds of plants on a 



56(i96°— 12 13 



