Aproveitamento de um fosfato natural parcialmente solubilizado pelas culturas do arroz, milho e soja: I. Resultados preliminares

In slightly acidic soils the effect of two rates of PARP (60 and 120 kg P2O5 per hectare) was compared to that of single superphosphate and of the original ground Araxá rock phosphate (ARP), both supplied to give 90 kg P2O5/ha. Testcrops were: upland rice, corn and soybeans. Main conclusions, based on yield data, and soil and leaf analyses were the following: (1) there was no statistical diferrence between yields obtained with PARP and SS which, however, were ussuallu higher than those provided for by ARP; (2) results from chemical analyses show that the PARP, as well as the SS, were a source of P, Ca and S to the three crops; (3) under the experimental conditions, there fore, the effect of the PARP was close to that of the SS rather than to the effect due to the ARP.Em solos pouco ácidos, pobres em P disponível, dois dos quais anteriormente com vegetação de cerrado, foram conduzidos ensaios destinados a comparar a eficiência de um fosfato natural parcialmente acidulado com ácido sulfúrico (FAPS) com a do super simples (SS) e a do fosfato de Araxá original. Usaram-se as culturas de arroz de sequeiro, milho e soja. Verificou-se que: (1) o FAPS deu produções que não diferiram estatísticamente das obtidas com o SS sendo maiores que as conseguidas com o FA; (2) os resultados das análises de solos e da diagnose foliar indicam que o FAPS funcionou como fonte de P, Ca e S

Aproveitamento de um fosfato natural parcialmente solubilizado pela cultura da cana-de-açúcar: I. Cana-planta

The relative efficiency of a partially acidulated and granulated rock phosphate, FAPS, containing 26% total P2O5, 10% citric acid soluble P2O5, 13% ammonium citrate soluble P2O5, 27% total CaO and 7% total S, was compared with that of both simple superphosphate (SS) and ground rock phosphate (FA). The experiment with the sugar cane variety NA 56-79 was set in a red yellow latosol, pH 5.1-5.5, low in P (4 ppm), and with and average available sulphur content (5 ppm as sul fate). The main conclusions were as follows: a) FAPS gave the same yield results provided by SS when used at the same rates based on total P2O5 content; b) sucrose content in the juice was increased by the highest level (16a kg P2O5 of application of FAPS; c) leaf analyses data suggest that FAPS has incre ased yield by supplying both P2O5 and S to the sugar-cane crop.Em um latossolo, com teor de P disponível entre baixo e médio foi instalado um ensaio destinado a comparar a eficiência de um fosfato natural parcialmente acidulado (FAPS) com a do super simples (SS) e a do fosfato de Araxá (FA) original, na cultura da cana-de-açúcar (cana-planta). Os dados obtidos mostraram que: (1) o FAPS deu uma produção que não diferiu estatisticamente da obtida com o SS, sendo superior ao FA como fonte de P2O5; (2) os dados de diagnose foliar sugerem que o FAPS e o SS funcionam como fonte de P e de S; (3) o teor de açúcares redutores no caldo aumentou em consequência da adubação fosfatada; (4) o FAPS, na dose mais alta, elevou o teor de sacarose do caldo

Estudos sobre a nutrição mineral do sorgo sacarino (Sorghum bicolor (L) Moench). I: deficiências de macro e micronutrientes e toxidez de alumínio, cloro e manganês

Sweet sorghum cv Brandes was grown in nutrient solution under stress of macro and micronutrients, as well as in the presence of toxic levels of Al, Cl and Mn. Symptoms of deficiency were observed in all cases, with the possible exception of Cu. Toxicity symptoms of the elements tested were also observed. As a rule, there was good agreement between abnormalities induced with those described in the literature for cereals. Dry matter production was affected in the following increasing order: -S = - Cu = - P = complete, -B, -Zn, -K, -Mo, -N, excess Mn, -Mg, excess Cl, -Fe, excess Al and -Ca. The following leaf contents correspond to deficiency level: N - 1.87%, P-0.14%, K-0.73%, Ca-0.40% (lower leaves) and 0.66% (upper leaves); S-0.16%; B-32 ppm (lower leaves) and 15 ppm (upper leaves), Cu-8 ppm; Fe-157 ppm (lower leaves) and 162 ppm (upper leaves); Mn-339 ppm (lower leaves) and 144 ppm (upper leaves); Mo-0.54 ppm; Zn-16 ppm. Leaf contents associated with toxicity symptoms were: Al-640 ppm; Cl-3.85%; Mn-1440 ppm, and, 1220, 2.37% and 445 ppm, respectively for lower and upper leaves. Nutrient requirements of weet sorghum were estimated to be in kg/ha: N-89.0, P-10.2, K-91.5, Ca-31.5, Mg-18.1, and S-11.6; in g/ha: B-90.0, Cu.61.0, Fe-1,704.0, Mn-256, Mo-2-4, and Zn-146. Only N and K significantly affected ethyl alcohol yield.Sorgo sacarino, cv Brandes, foi cultivado em solução nutritiva deficiente em macro e micronutrientes e com excesso de alumínio, cloro e manganês. Foram obtidos sintomas das deficiências e excessos provocados no meio e o material foi analisado. Obteve-se uma estimativa das exigências nutricionais. Análises tecnológicas do colmo, mostraram os efeitos das deficiências de nitrogênio, fósforo e potássio sobre as mesmas