FIELD CROPS. 333 



Experiments to determine the relative value of fertilizers supplying nitrogen were 

 begun in 1890 and the erops grown, given in their order, were oats, rye, soy beans, 

 oats, soy beans, oats, soy beans, oats, oats, elover, and potatoes. The relative effi- 

 ciency of the different materials was found to be as follows: Nitrate of soda 100, liarn- 

 yard manure 90, snli)hate of annnonia 89, dried blood 86, and the plats without nitro- 

 gen 68. Owing to the hunuis and mineral su])stances furnished by T)arnyard manure 

 in addition to nitrogen, the autlior considers its ethciency really higher than the 

 availability of nitrogen alone would show. The results further showed that the effi- 

 ciency of sulphate of ammonia is largely increased when the soil is well supplied 

 with lime. 



Plowing under the stubble and roots of soy l)eans and clover was found to be very 

 advantageous to subsequent crops. The plats on Avhieh this test was made had 

 received no nitrogen in the fertilizer for 16 seasons, still after this long period pota- 

 toes on clover sod gave a crop equal to 95.8 per cent of the yield on plats which had 

 yearly been given a fair amount of fertilizer containing nitrogen. This season the 

 nitrogen plats yielded 219.3 bu. of potatoes per acre, or an increase of 10.3 bu. as 

 compared with the no-nitrogen plats. 



Comparative tests with muriate and high-grade sulphate of potash have been in 

 progress since 1892. Both salts were applied yearly at the rate of 400 lbs. per acre, 

 but this season only 250 lbs. Avere used. Considering the results for the entire period, 

 clover, cabbage, and soy beans generally gave the best returns on the sulphate plats, 

 while corn, grasses, oats, barley, vetches, and sugar l^eets gave equally good yields 

 on the muriate plats. The sulphate i>lats produced the best quality of potatoes and 

 sugar beets. Considering all the crops except the clover, the efficiency of the muri- 

 ate was 98.1 jier cent of that of the sulphate, and taking into consideration only those 

 crops which showed a preference for the sulphate, its efficiency was 88.6 per cent of 

 that of the sulphate. The conclusion of the authors favors the use of the sulphate 

 at jtresent prices. The results with early and late garden crops were also in favor of 

 the use of sulphate of potash, especially in the case of early crops. 



The series of experiments with nitrate of soda, dried blood, and sulphate of ammo- 

 nia in progress since 1891, showed that up to 1898 nitrate of soda was with one 

 exception the most efficient source of nitrogen. During the j^eriod of these tests 

 only commercial fertilizers were applied. 



From 1890 to 1893 inclusive, dissolved boneblack, ground South Carolina rock, 

 ground Florida rock, Mona guano, and phosphatic slag were compared on the basis of 

 their money value, i.e., the cost of quantities applied being the same in all cases. 

 The soil had been liberally supplied with nitrogen and potash since the beginning 

 of the experiment, but no phosphate has been applied since 1893. The results for 

 the entire period indicate that the liberal use of natural phosphates produces profit- 

 able crops and that in a long series of years their substitution, at least in part, for 

 the higher priced dissolved phosphates may prove econouiical. None of these nat- 

 ural phosphates seemed suitable for cruciferous crops. There was practically no dif- 

 ference in the economic results from South Carolina rock, INIona guano, and phos- 

 phatic slag. The quantitj- of Florida phosphate used contained more phosphoric- 

 acid than any of the others but it becomes soluble very slowly. For ordinary farm 

 and garden crops the use of the natural phosphates in connection -with, a moderate 

 quantity of one of the dissolved phosphates is recommended. A comparison of 

 phosphates on the basis of an equal application of phosphoric acid, in progress for 

 three years, showed that phosphatic slag furnished phosphoric acid in a very avail- 

 able form, yielding about as much as dissolved l)onel)lack; that the phosphoric acid 

 of Florida soft phosj)hate was renilere<l available with great slowness; and that 

 steamed bone meal appeared inferior in availability to raw bone meal. 



The results for the twelfth season of a soil test with grass are reported, in which 

 the same fertilizers or combinations were ai)i)lied to the same plats continuously. 



