Efficiency of Polyhalite as a Sulphur Source on Wheat in Argentina

Magen, H.1, Melgar, R.J.2, Ventimiglia, L.3, Torrens, L.3, and Vale, F.4 1International Potash Institute (IPI), Zug, Switzerland ([email protected]); 2INTA, Pergamino, Buenos Aires, Argentina; 3INTA, 9 de Julio, Buenos Aires, Argentina; 4International Potash Institute (IPI), Zug, Switzerland; IPI Coordinator for Latin America ([email protected])

Introduction Results and discussion Polyhalite is one of a number of evaporate minerals containing potassium (K). Polyhalite (dihydrate) is a single crystal complex with two molecules of water of crystallization. It Significant response to S. is not a mixture of salts. The chemical formula is: K2Ca2Mg(SO4)4·2(H2O), and contains No significant response to K, Ca or Mg.

48% SO3, 14% K2O, 6% MgO and 17% CaO. One important characteristic of Polyhalite is the prolongued release and availability of nutrients, especially in relation to sulphur (S). Grain yield Objective 7,000 The objective of this research was to compare the agronomic efficiency of fertilizer bulk blends that include Polyhalite, on wheat production in Argentina, under field conditions. 6,000 6,345 ) 6,165 6,089 -1 5,000 5,934 5,919 a a a a a 4,000 4,719 Material and methods b • Place: Nueve de Julio, Buenos Aires, Argentina. 3,000 • Soil: The main parameters of the arable layer (0-20 cm) of the trial soil were: pH = 5.9; 2,000

-1 -1 -1 Grain yield (kg ha organic matter = 29 g kg ; phosphorus (P)-Bray = 9.8 mg kg ; S-SO4 =7.1 mg kg ; K = 1.23 cmolc kg-1; calcium (Ca) = 6.5 cmolc kg-1; magnesium (Mg) = 1.36 cmolc kg-1. 1,000 0 The soil is of sandy loam texture, and the low organic matter and available S-SO4 levels indicate a potential for nutrient response. Control - SSP MAP + MAP + MAP + MAP + • Experimental design: Randomized complete block design with four replications, MAP (No S) gypsum 100 kg ha-1 200 kg ha-1 300 kg ha-1 comprising six treatments. Polyhalite Polyhalite Polyhalite • Treatments: different blends of monoammonium phosphate (MAP) plus sources of S, -1 -1 in order to apply a single rate of P2O5 (30 kg ha ) and variable rates of S (0 to 57 kg ha ) at sowing, according to Table 1. Protein values obtained were low. The only treatment that reached the commercial base was the control (11%). The level of N fertilization was probably lower than necessary.

Protein %

12

10 11 a 8 9.1 9.3 9.3 9.2 9.2 c b b b bc 6

Protein (%) 4

MAP +gypsum MAP + Polysulphate Polyhalite (100 kg ha-1) 2 0 Table 1. Description of treatments Control - SSP MAP + MAP + MAP + MAP + MAP (No S) gypsum 100 kg ha-1 200 kg ha-1 300 kg ha-1 Treatment Fertilizer N P2O5 S K2O CaO MgO Polyhalite Polyhalite Polyhalite kg ha-1 1 Control - MAP (No S) 58 6 30 - - - - Greater hectoliter weight = greater yield of flour. 2 Single superphosphate (SSP) 158 0 30 19 - - - Commercial standards require a value of 79 or higher. 3 MAP + gypsum 167 6 30 19 - - - There were statistical differences and SSP resulted in the lowest. 4 MAP + 100 kg ha-1 Polyhalite 158 6 30 19 14 17 6 5 MAP + 200 kg ha-1 Polyhalite 258 6 30 38 28 34 12 Hectoliter weight 6 MAP + 300 kg ha-1 Polyhalite 358 6 30 57 42 51 18 Note: Treatment 1: 58 kg ha-1 MAP (11-52-0-0S). Treatment 2: 158 kg ha-1 SSP (0-19-0-12S). Treatment 3: bulk blend of 58 kg ha-1 MAP and 109 kg ha-1 granular gypsum (0-0-0-17S). 88 Treatments 4 to 6: bulk blends of 58 kg ha-1 MAP and Polyhalite (0-0-14-19S -17CaO - 6MgO), respectively 100, 87 87.6 200 or 300 kg ha-1 of Polyhalite. 86 a 86.6 86.4 85 a • The site cropped to wheat was sown under no-till on June 16, 2016, with a Klein a 85.8 84 ab variety at a density of 278 seeds m-2. 84.5 83 • Fertilizers were applied in the seed line with a planter. ab -1 82 • At sowing, 167 kg of urea was applied broadcast. Nitrogen (N) at 75 kg N ha was 82.4 applied as urea, prior to emergence on June 29, 2016. 81 b Hectoliter weight (kg/hl) 80 • Evaluations 79 • Grain was harvested mechanically on December 10, 2016, and yield converted to kg Control - SSP MAP + MAP + MAP + MAP + ha-1 of grain. MAP (No S) gypsum 100 kg ha-1 200 kg ha-1 300 kg ha-1 • Grain samples were taken for testing for commercial quality, which included Polyhalite Polyhalite Polyhalite hectoliter weight, protein and gluten content. Different letters within columns indicate statistically significant differences.

Conclusions • The results highlight the importance of S in improving wheat yields in Argentina. • This nutrient should not be lacking in the productive approaches used in the region. • A rate of 19 kg S ha-1 was sufficient to achieve a yield response. • Polyhalite was an efficient source for supplying sulphur for wheat fertilization in Argentina.

IPI is a non-governmental and non-profit organization based in Zug, Switzerland. Founded in 1952 by German and French potash producers, it is now supported by potash producers in Europe and the Near East. IPI is governed by a Technical Secretariat and Board which convene several times each year. A major part of IPI’s work is carried out by its team of field agronomists, or coordinators, who work closely with researchers, government offices, extension and agribusinesses around the world. IPI’s mission is to develop and promote balanced fertilization for higher yields and more nutritious food, ensuring SINCE sustainable production through the conservation of soil fertility for future generations. This poster was presented at the IPNC 2017, Copenhagen 21-24 August 2017 www.ipipotash.org