Pumpkin Fertilizer Requirements

First of all, you have to take into consideration the soil condition of your field through semiannual or annual soil testing, before applying any fertilization or tillage method. No two fields are the same, nor can anyone advise you on fertilization methods without taking into account your soil’s test data, tissue analysis, and crop history of your field. However, we will list the most common pumpkin fertilization schemes (general recommendation) used by a considerable number of farmers.

As in other fruit crops, it is essential to apply a balanced fertilization program and avoid over-fertilization (excessive use of nitrogen, for example), which will lead to plant toxicities, loss of nutrients due to run-off and excessive vegetative growth (in the expense of fruit production). Moreover, overuse of nitrogen-rich fertilizers, especially during early developmental stages, may decrease the ability of female flowers to set.

Fertilizers may be broadcasted in the whole field or banded in plant rows. Keep in mind that when broadcasted, higher amounts of fertilizer are needed. This technique is generally not recommended, especially in fields with intense weed problems. 

Many (organic) farmers use animal manure or compost to supply their crops with the nutrient needed, improve soil organic matter, or as a complementary application combined with some chemical-synthetic fertilizers. Fowl manure (e.g., from chickens) is considered to be the richest in N-P-K (2.1% N, 1.6% P, and 1.0% K), and 5 tones per hectare are usually incorporated in the field as a base dressing 4-6 weeks before planting the pumpkins. In general, pumpkin growers use, on average, 110-160 kg N (or 260 kg urea/hectare), 30-45 kg P₂O₅, 45-200 kg K₂O, 90-130 kg CaO and 40-60kg MgO per hectare (98-143 lb N or 232 lb urea, 27-40 lb P₂O₅, 40-178 lb K₂O, 80-116 lb CaO, 37-53.5 lb MgO per acre). Depending on the field and the results of the soil analysis, the pumpkin grower may also need to add 11 kg of sulfur, 1.12 kg of actual boron, and 5.6 kg of actual zinc per hectare (10 lb S, 1 lb B, 5 lb Zn per acre respectively). 

Keep in mind that the amounts mentioned above are relatively high and should be reduced when the pumpkins succeed with legumes in the field (especially for the N) or the soil analysis test shows sufficient amounts of nutrients on the field. For example, if soil nitrate is more than 50 ppm on the soil, then the amount of N fertilizers added should be reduced to 50 kg/ha (44.6 lb/acre). Insufficient nutrient levels in the soil, 20 kg/ha of P (18 lb/acre) and 0-20 kg of K (0-18 lb/acre), are more than enough to cover pumpkin plants’ needs. 

To avoid nutrient leaching (especially for N), pumpkin growers split the total amount of fertilizers needed in more doses. They start by offering 50-70 kg/ha N (45-62 lb/acre), the total amount of P (P₂O₅), 90-120 kg/ha K₂O and 20-30 kg/ha MgO (80-107 lb K₂O and 18-27 lb MgO per acre) as a base fertilizer before planting and continue with the side dressing by applying 55-70 kg N, 130-180 kg K₂O and 20-30kg MgO per hectare (49-62 lb N, 116-162 lb K₂O and 18-27 lb MgO per acre) divided into 2-4 applications. Later, they may make any required corrections by applying foliar fertilizers. In some cases, farmers may perform foliar spray with sodium molybdate in the stage of 3-4 leaves. Usually, the side-dressing, especially for nitrogen, is applied right before vine growth starts, to avoid any negative effect on fruit set and yield. The rest of the nutrients can be applied in 2 doses, 1 around 5 weeks after transplanting and the other 4 weeks later. 

When a drip irrigation system has been installed and used in a pumpkin field, many farmers choose to fertilize their crop through fertigation (fertilization + irrigation). Farmers inject water-soluble fertilizers inside the drip irrigation system. This way, they can provide the nutrients gradually and give the plant the proper time to absorb them. Fertigation generally starts about two to three weeks after transplanting pumpkin seedlings.

However, these are just common patterns that should not be followed without doing your own research. Every field is different and has different needs. Checking the soil nutrients and pH is vital before applying any fertilization method. You can consult your local licensed agronomist.

References

• https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0004/311485/Pumpkin-production.pdf
• https://extension.uga.edu/publications/detail.html?number=B1180&title=commercial-production-and-management-of-pumpkins-and-gourds
• https://agriculture.gov.tt/wp-content/uploads/2017/11/how-to-grow-pumpkin.pdf
• https://doa.gov.lk/hordi-crop-pumpkin/

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Pumpkin Fertilizer Requirements

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