42 CULTIVATION METHODS AND ROTATIONS FOR GREAT PLAINS. 



little or no significance. At North Platte the results were very 

 slightly in favor of rotation in 1907 and very markedly so in 1908. 

 The average results of the three years were therefore in favor of rota- 

 tion, so the results of 1909 can not be considered of great significance. 

 They were due to the fact that a severe freeze about the first of May, 

 followed by high winds, injured the crops on those fields that had 

 had the best tillage and had consequently produced the most vigorous 

 growth more than it did those on the poorer tilled fields where the 

 growth was less advanced. This is not an infrequent occurrence 

 throughout the Great Plains, but it can not be used as a reason for 

 practicing continuous cropping instead of crop rotation. The crops 

 at Amarillo, Tex., were so near a practical failure that the fact that 

 continuous cropping gave slightly better results can not be considered 

 of great significance. It may therefore be safely asserted that the 

 net results of all the tests were strongly in favor of rotation. This 

 becomes more apparent when we consider that the best rotation in 

 the test gave better results than continuous cropping in all except 

 three instances, and the average results showed a difference in favor 

 of rotation amounting to $2.38 per acre; or calculated in bushels of 

 wheat, oats, and barley, 3.91, 7.93, and 6.26 bushels per acre, 

 respectively. 



At first sight it might appear that there was little uniformity in 

 the rotation giving the best average results in all the tests or in the 

 ones giving the best results at any given station where two or more 

 years 7 results have been obtained. A more careful consideration 

 will show, however, that some general uniformity in results is indi- 

 cated. In just half the tests either rotations Nos. 1 or 6 gave the 

 best results. These two rotations are identical except that in No. 1 

 wheat was sown on disked corn stubble and in No. 6 barley was sub- 

 stituted for the wheat. The other barley rotation, No. 7, gave the 

 best results in three tests. Nos. 3 and 4 gave the best results in two 

 tests each, while No. 2 gave the best results in only one test. 



Rotation No. 9 failed to give the best results in any test. This 

 fact is very significant, as it brings to notice an important feature of 

 crop rotation. This is, that one sequence may give the best results 

 at a station when the plowing is done at one time of year, while the 

 opposite sequence gives the best results when the plowing is done at 

 another time. It seems that the oats-wheat-corn sequence makes a 

 bad combination with spring plowing at all the stations. It seems 

 likely that further investigation will show that there are other com- 

 binations which are to be avoided. 



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