Abstract
Investigations were made on the characteristics of sugarcane plants variety cultivated in ratooning for four years, and on the effects of cultivation on the chemical properties of the soil.
The results are summarized as follows:
1. The budding position was elevated as ratooning was repeated. The following results were also demonstrated on sugarcane from repeated ratoonings, more tillers, a wider hill spread, more slender stalks, shorter millable stalks, and finally a lighter weight per stalk.
2. Sugarcane yield increased gradually between the new planting and the first ratooning and the second one, but in the third ratooning, it declined by 11% from the second ratooning, and declined somewhat in the fourth ratooning.
3. Brix and polarization of the cane juice increased slightly as ratooning was repeated.
4. Exchangeable cations in the soil declined noticeably after repeated ratoonings. Especially, calcium and potassium ions in the soil after the second ratooning declined to about one half of those contained in the control-bare ground soil. Magnesium ionization also declined when ratooning was repeated.
5. The soil cultivated in the successive ratoonings decreased in PH. Humus increased slightly because of the accumulation of rotted sugarcane roots.
6. As a result of these experiments, it appears that three ratoonings following a new planting is the limit of successive croppings of sugarcane for economical returns. Also, an application of sufficient amounts of cations to the soil would be necessary if sugarcane is to be newly planted in the same field after repeated ratooningss.
