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Potato Fertilization

Fertilizer application, rule of thumb:

Apply sufficient quantities of Nitrogen (N), Potassium (K) and Phosphates (P) to achieve optimal crop yields, tuber size and quality. Conducting a soil test will enable you to determine the correct amounts of fertilizer to be applied. The recommended nutrient application for main season crop potatoes is as follows:


Low (Kg/hector) High

Nitrogen (N)

95-170; 210Lbs – 375,  per 2.47Acres, Being: 85-152#/A

Phosphate (P)

50-125; 110Lbs – 275, Being: 45 - 111

Potash (K)

120-305; 264Lbs – 673, Being: 107 - 272

In case you decide to use organic manures, you will need to proportionately reduce the amounts of fertilizer applied based on the manure’s nutrient value.

Crop Process
A 50 pound bag of dry fertilizer at example labeled 10-20-20 is 10% Nitrogen, 20% Phosphate, and 20 percent Potash. In our soils, without soil testing, we have produced a low of 5 times seed potato planting pounds planted during a drought, to an exceptional high of 20 times in one plot, the overall average being a typical 7 times our planting pounds. In an exceptional year we had 238,500 pounds from 8 acres planted at 2,187 pounds per acre with 500 pounds of 10-20-20 Micros applied and high seasonal rains. We currently plant 34" width rows at approximately 2,187 cut seed potato pounds per acre. We have been applying dry fertilizer 5-10-10 and 10-20-20  (in 2016 and prior seasons) at approximately 200 and 250 manually metered pounds per acre distributed by the 2 row potato planter scattered upon the seed furrow, in yearly to every other year crop rotation with field corn. Compared to 85 pounds, 45 pounds, 107 pounds per acre as minimum suggested, we have typically applied; 50 pound of N (Nitrogen), 100 pounds of P (Phosphorus) and 100 pounds of K (Potassium) per acre, according to the percentage/weight formula. 19-19-19 is considered by many as the "sweet spot" of fertilizer for potatoes. The soils we utilize here trend below the micronuetrients said to be needed today. We have not particularly attended to sulfur, molybdenum, nor cobalt.
The field corn we crop, is currently harvested with a New Idea Corn Picker, and JD 4425 Combine, mowed, disced, and plowed under with moldboard plowing at a depth no less then 8 inches. It is best to chop up the stalks in the Fall right after harvest. We Mow, Disc, Plow, Disc, do some Harrowing then, and Plant. Potatoes seed cut and planted in early Spring 2 to 3 weeks before our frost date of May 18th, and are ready for harvest Mid August. Watching the weather forecast we plant as early as we may.
Weed herbicides are applied by label from low to medium application, after planting prior to plant sprout, is within immediate to 2-3 weeks after planting in early Spring cold weather planting, of Dual Magnum II (Metolachlor) (or other generic label) for grass control, and Tricor DF (Metribuzen) by brand label for broadleaf weed control, mixed in water and sprayed upon the plot planted soils after hill/planting. 50 or less gallons water mix per acre. Moisture, rain (not flooding) is required to seal the herbicide after spray application. A drought Spring can hurt the herbicide soil seal. Poast and Tricor mix may be reapplied, and used in conjunction with prior weed cultivation, in problem plots prior to blossom time, or earlier post potato plant sprouting for weed control by product label. Typically we no longer do follow-up hilling for economic, time, and herbicide soil seal weed control reasons, so it is "a low hill" process these days, which does slightly degrade production. As needed, insecticide for Colorado Potato Beetle is applied as necessary by topical water mixed over-spray, which the bug consumes on the plant leaves and dies within the same day Alias by brand name, per label application. Follow-up applications are completed at 7 day intervals as needed by label. Liquid Copper or other Fungicide is mixed and applied to plants per label in the same over-spray manner, to arrest Early Blight on the plants if necessary, as many application times as needed. An application added to topical spray was Micronuetrients as well for vigorous plant health. We leave the field crop in ground as long as we can for a full potato maturation, prior to either and/or defoliation, and flail mowing the vine plants and any post late season weeds. When needed, Diquat brand herbicide is applied by label, minimum of 3 weeks prior harvest, before flail mowing.
Harvests are completed with volunteers. We use mechanical 1Row harvesters: potato plow (middlebuster) as ultimate backup, old chain diggers both PTO power driven, and ground drive, and a new Spedo vibration root harvester (good high hills required), to get the potatoes atop the soil surface, for volunteers pick up potatoes into 5 gallon buckets, which are dumped into watermelon bins (gaylords) either by transport or in field, handled on pallets with our pallet forks either on the 3 point hitch or front-end loader on bigger tractors. The gaylords typically weigh in at 850-950 pounds or more. 37Hp engine AG class, weighted tractors are necessary to lift and carefully handle the binned pallet potatoes afield with the 3Point mounted pallet fork. We have a 2011 Kubota L3800HST 37Hp tractor with rear Wifo 3 Point pallet fork, full rack front suitcase weights and rear in-tire ballast. A 1980 J.D. 1050 tractor, same. And a 1994 Case IH 4210, 72Hp tractor with Wifo rear 3 point hydraulic mast forklift (overkill). One volunteer has a NH Boomer 50 tractor with pallet forks on the FEL which can handle our palletized potatoe bins. A 50 gallon tank CropCare 3Pt. Sprayer with 20ft. booms is used now, on mostly rolling hills plots. Originally I had rigged a Farmall Cub tractor with a 25 gallon 3Row sprayer, before acquiring the CropCare unit.

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