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Copy link Polysulphate Alfalfa Trial on Matherton Silt Loam
8.2
Yield increase
Polysulphate improved quality parameters and yield in Alfalfa, boosting 4th cutting yields in Wisconsin, USA
Whitewater, Wisconsin, USA 2022
8.2
Key Conclusions
Providing adequate soil fertility is crucial for maintaining alfalfa productivity and quality. Polysulphate in combination with MOP is an excellent source of K and S for season-long release of nutrients to replace those removed with each cutting.
Objective
Demonstrate the benefit of granular Polysulphate as an annual topdress application, applied after first cutting, in combination with MOP to target potassium and sulfur removal requirements for 6 ton/acre/yr alfalfa production in the upper Midwest.
Trial Details
Trial station
Whitewater, Wisconsin, USA
Crop
Alfalfa
Product
Polysulphate®
Assessments
Yield and forage quality
Treatments
- An unfertilized control (treatment 1) received no supplemental K or S.
- Three treatments were designed to supply the K and S removed by a 6 ton/acre/yr alfalfa crop: (Treatment 2) a grower standard practice (GSP) receiving MOP at 583 lbs/A,(Treatment 3) MOP (583 lbs/A) + AMS (150 lbs/A),(Treatment 4) MOP (540 lbs/A) + Polysulphate (187.5 lbs/A);
- These treatments were top-dressed between 1st and 2nd cutting on June 10th, 2022.
- An additional two treatments received the same fertilizer sources and total amounts as treatments 3 and 4 but were split-applied on June 10 and August 26 (after 3rd cutting) according to local practices for intensively managed alfalfa production.
- All treatments were replicated four times in an RCBD.
Treatments
- An unfertilized control (treatment 1) received no supplemental K or S.
- Three treatments were designed to supply the K and S removed by a 6 ton/acre/yr alfalfa crop: (Treatment 2) a grower standard practice (GSP) receiving MOP at 583 lbs/A,(Treatment 3) MOP (583 lbs/A) + AMS (150 lbs/A),(Treatment 4) MOP (540 lbs/A) + Polysulphate (187.5 lbs/A);
- These treatments were top-dressed between 1st and 2nd cutting on June 10th, 2022.
- An additional two treatments received the same fertilizer sources and total amounts as treatments 3 and 4 but were split-applied on June 10 and August 26 (after 3rd cutting) according to local practices for intensively managed alfalfa production.
- All treatments were replicated four times in an RCBD.
Results
- Polysulphate increased Alfalfa yield by 8.2% when compared to grower standard practice
- Supplying only K increased total cumulative yield by approximately 1 ton/A. On average, providing S resulted in an additional 0.4 ton/A cumulative yield gain.
- Treatment differences were most pronounced at the 4th cutting.
- For one-time fertilizer applications (treatments 2, 3, 4) the MOP + Polysulphate had the highest 4th cutting yield and cumulative yield demonstrating the value of a sustained release source of S for alfalfa production
- Split-applications of K and S (treatments 5, 6) resulted in the greatest 4th cutting yields.
- Sulfur fertility promoted increases in quality parameters like crude protein, relative feed quality, and milk per ton of hay (data not shown)
The four-in-one natural fertilizer
