This poster was presented at the
2019 ASA-CSSA-SSSA International Annual Meeting, San Antonio, Texas
10-13 November 2019
Providing an adequate supply of nutrients is important for high yields and is essential to maintain high quality and profitable yields in integrated systems. Potassium chloride is the most used potash fertilizer in Brazil. However, there are other minerals composed of sulfates that may be considered. Polyhalite is a natural occurrence multi-nutrient mineral (11.7%-K, 19%-S, 3.6%-Mg, and 12.1%-Ca), whose potential to be a fertilizer for high yield and quality forage and crop needs to be investigated. The objective of this research was to evaluate the effect of K source fertilizers on maize Piatã grass yield and nutritional status in crop-livestock integrated systems (CLIS).
The field experiment was carried out in São Carlos, SP, Brazil in a Typic Hapludox, during the two growing seasons. The CLIS is sown with maize (Zea mays cv. AG 8690-Pro3) together with Piatã grass (Urochloa brizantha). Treatments comprised two K sources: polyhalite and KCl (60% K2O) and five ratios of polyhalite:KCl. The treatments were: i) Control (no K, S, Mg or Ca); ii) KCl 100%; iii) KCl 87,5% + Polyhalite 12,5%; iv) KCl 50% + Polyhalite 50%; v) KCl 12,5% + Polyhalite 87,5%; vi) Polyhalite 100%. The treatments were applied in the sowing and topdressing fertilization. Piatã grass utilized the residual fertilization of K for growth. Maize and grass yield obtained with the polyhalite and KCL mixture was significantly higher (p <0.05) than the control.
The best results of dry matter yield of maize and Piatã grass were obtained with the treatments with the highest ratios of polyhalite. These values were 20% to 36% higher than the best yield obtained in control. The treatments were also efficient in increasing S in soil and exportation of K, Mg, and by maize. This study demonstrated that polyhalite is an alternative source of K, Ca, Mg, and S.
by Alberto C. C.Bernardi, Gilberto B. Souza and Fabio Valle.
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