English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Durante os anos de 1957 a 1960, instalaram-se cêrca de 400 experiências de adubação para algodoeiro, nas principais zonas de exploração dessa malvácea no Estado de São Paulo. Dessas experiêncis, por diversas causas, só foram aproveitadas 216 para os estudos de fertilidade. Os resultados indicaram maior reação para o fósforo, pequena para o nitrogênio e raramente para o potássio. Estudando-se os teores de fósforo solúvel em H2SO4 0,05 N, foi possível diferenciar dois tipos de reação, um para solos arenosos e outros para argilosos, e estabelecer os respectivos níveis de fertilidade. Foram estabelecidos níveis, apenas preliminares, de reação ao nitrogênio, em virtude do pequeno número de experimentos com resposta significativa a esse elemento. Dado o pequeno número de experiências com reação ao potássio, nenhuma indicação se conseguiu sôbre os níveis de fertilidade para êsse elemento. Verificou-se relação entre o pH do solo e a reação à adubação fosfatada, diminuindo a ação desta com a elevação do pH. As experiências encontradas na literatura, abrangendo os mesmos solos e utilizando os mesmos extratores, permitiram confirmar os níveis de fertilidade preconizados para as condições do Estado de São Paulo. During the years of 1957 through 1960. about 400 experiments for cotton fertilizing were installed in the main districts of exploitation of this malvacea. For some reason or another, only 216 out of these experiments were used for the studies about fertility. The results obtained from the fertilization indicate that the major reaction is for the element phosphorus, in a small scale for the nitrogen and, for potassium, in less than 5% of the whole of the experiments. When studying the contents of phosphorus soluble in H2SO4 0.05 N, it was possible to differentiate two types of rection: one for sandy soils and the other for the clay soils, thus establishing the respective levels of fertility. Another method investigated was that of the oxalic acid + potassium oxalate 1 N as extractor of phosphorus, which did not show adequate to foresee the requirements of phosphorous fertilization. The levels of nitrogen established through this experimentation should be considered as a preliminary attempt, on account of the small number of trials with reaction to nitrogenous fertilization. Due to the small number of trials with reaction to potassium, no indications were possible to be obtained for this element. It was also found that there is a relation between the pH of the soil and the reaction to phosphorous fertilization, lessening its action with the raising of the pH. The experiments as located in the literature, referring to the same soils and utilizing the same extractors, allowed the confirmation of the divulgated fertility levels

Níveis de fertilidade dos solos do estado de São Paulo para a cultura algodoeira. I- Os teores de fósforo, nitrogênio e potássio