Issue 5 2019
 
Precision feeding the soil that feeds our crops and us

‘Use targeted and balanced crop fertilization’ – it’s one of our main messages.

It’s advice that we need to repeat at every opportunity, clearly and with examples or illustrations of the benefits. And now we want to share some new evidence with you from South America of how using Polysulphate in a balanced crop nutrition regime helps farmers to reap rewards.
 

Better yield potential from start to finish

Argentina and Paraguay, like other South American countries, can only continue with prolific grain production if there is balanced fertilization. Maintaining adequate soil availability of the main nutrients (N, P, K and S) has become a challenge. Starter fertilizer blends are often not up to the job of giving the crop all it needs to yield to the maximum. So, researchers in South America, with the support of the International Potash Institute, set up field trials. They compared how bulk fertilizer blends containing Polysulphate (which gradually releases S, K, Mg and Ca) at three different ratios, compared with other formulations being used, like MAP+gypsum.

Cropping with wheat, maize and soybean came under scrutiny in Argentina. Crop response to S was obvious at all growth stages. Average yield increases were up 29%, 24% and 39% respectively. Of the three crops, only soybean yielded significantly more in response to increased rates of Polysulphate.

The conclusion is evident: Polysulphate can be very effective as part of fertilizer blends applied at the pre-plant stage. On S-deficient soils, Polysulphate is a suitable source of this nutrient and has the same positive effect as other fertilizers currently used to support grain production in South America. In addition to S, Polysulphate provides other essential nutrients - K, Mg, and Ca.
 
Soybean yield response to the fertilizer treatments at Mercedes, Argentina. Similar letters indicate non-significant statistical differences between treatments at P=0.05.
Measuring the residual effect

Meanwhile, in Paraguay the trial looked at soybean treated with different blends of starter fertilizer followed by maize. Both crops showed significant yield increases from the higher K dose. The use of Polysulphate also gave rise to a significant soybean yield increase.

Understanding our role

Sharing the evidence that supports targeted and balanced fertilization is an important responsibility for us all. If you need more details on these trials in South America then see the research report. But in the meantime, we hope this adds another example to your portfolio of evidence of the remarkable, productive synergy that can be achieved in farmers’ fields with fertilizer blends containing Polysulphate.
Soybean plant samples from the Mercedes, Argentina study after harvest. Photo by R. Melgar.
This research paper was written by Dr. Ricardo Melgar from Argentina, who conducted these experiments. Sadly, Ricardo passed away shortly after finishing this paper. He dedicated his career to soils, crops fertilization and plant nutrition. We have lost a valued friend and an authority for soil science and agronomy. We will miss him greatly and will always cherish his great contribution to science.
 
Mined in the UK, ICL is the first – and only - producer in the world to mine polyhalite, marketed as Polysulphate