Polysulphate Cabbage Trial in Brazil
13
Piedade, Sao Paulo state, Brazil 2017
13
Key Conclusions
Partially replacing KCl with Polysulphate fertilizer increases cabbage crop yield by up to 13% compared to KCl alone. Adding Polysulphate to the fertilizer blend also increases plant vigor, and reduces the incidence of black rot (Xanthomonas campestris).
Objective
To evaluate the yield and quality of the cabbage (Brassica oleracea) when KCl is substituted with Polysulphate as the source of potassium.
Trial Details
Trial station
Piedade, Sao Paulo state, Brazil
Crop
Cabbage
Product
Granular Polysulphate
Assessments
Yield, incidence of black rot in the leaves, and plant vigor
Treatments
This randomized block trial consisted of 4 replicates with 7 different treatments. With the exception of the control, the treatments consisted of different combinations of KCl and Polysulphate with the total K2O application rate remaining at 200 kg/ha. In October 2016 each treatment was applied (broadcast) to the soil surface in 4 equal applications the day before planting and at 14, 28, and 42 days after planting.
At planting, all treatments were fertilized with 400 kg/ha of P2O5 (MAP), broadcast and incorporated into the soil, and 200 kg/ha of N (urea) applied at the same time as the initial treatment applications. The crop was harvested in January 2017.
Treatment | KCl | Polysulphate | K2O | P2O5 | N (urea) |
---|---|---|---|---|---|
% | % | kg/ha | kg/ha | kg/ha | |
T1 control | 0 | 0 | 0 | 400 | 200 |
T2 | 100 | 0 | 200 | 400 | 200 |
T3 | 80 | 20 | 200 | 400 | 200 |
T4 | 60 | 40 | 200 | 400 | 200 |
T5 | 40 | 60 | 200 | 400 | 200 |
T6 | 20 | 80 | 200 | 400 | 200 |
T7 | 0 | 100 | 200 | 400 | 200 |
Treatments
This randomized block trial consisted of 4 replicates with 7 different treatments. With the exception of the control, the treatments consisted of different combinations of KCl and Polysulphate with the total K2O application rate remaining at 200 kg/ha. In October 2016 each treatment was applied (broadcast) to the soil surface in 4 equal applications the day before planting and at 14, 28, and 42 days after planting.
At planting, all treatments were fertilized with 400 kg/ha of P2O5 (MAP), broadcast and incorporated into the soil, and 200 kg/ha of N (urea) applied at the same time as the initial treatment applications. The crop was harvested in January 2017.
Treatment | KCl | Polysulphate | K2O | P2O5 | N (urea) |
---|---|---|---|---|---|
% | % | kg/ha | kg/ha | kg/ha | |
T1 control | 0 | 0 | 0 | 400 | 200 |
T2 | 100 | 0 | 200 | 400 | 200 |
T3 | 80 | 20 | 200 | 400 | 200 |
T4 | 60 | 40 | 200 | 400 | 200 |
T5 | 40 | 60 | 200 | 400 | 200 |
T6 | 20 | 80 | 200 | 400 | 200 |
T7 | 0 | 100 | 200 | 400 | 200 |
Results
- Polysulphate increased cabbage vigor and reduced the risk of black rot (Xanthomonas campestris).
- Partial replacement of KCl with Polysulphate increased crop productivity.
- The results indicate that the ratios with between 40 and 80% Polysulphate in the blend with KCl are the most beneficial, even in high fertility soils.