Application of mineral and organic fertilizers in hotbed and greenhouse farming

Soil used in greenhouse and hotbed farming contains all the nutrients necessary for the plant, and when obtaining ordinary average harvests, additional fertilizer application is not required. However, as experiments by research institutions and the practice of Stakhanovite vegetable growers have shown, the use of fertilizers in protected ground, especially as top dressing, has fully justified itself and yields excellent results.

A participant of the All-Union Agricultural Exhibition, Comrade D. V. Vasilyeva, a team leader at the "Vyborgsky" state farm, obtained a harvest in 1938 of 20.7 kg from each of her 1,758 frames. In addition to carrying out standard agricultural practices, she widely practiced top dressing of plants in hotbeds with mineral fertilizers. She fertilized cucumbers, for example, with a solution of a mixture of superphosphate and saltpeter (5–6 times during the growing season, at 30–35 g of the mixture per frame per one irrigation).

Comrade Voronina's team from the "Kikerino" state farm applied top dressing with superphosphate in the amount of 25–35 g and potassium salt — 10–15 g per frame during each irrigation. In 1938, the team received a vegetable harvest of about 46 kg per frame.

Summarizing the experience of Stakhanovites and data from research work, the following approximate compositions of fertilizers and top dressing in protected ground can be recommended:

A solution of saltpeter or ammonium sulfate — 40 g per 10 l of water.

A solution of saltpeter or ammonium sulfate 20 g — superphosphate 10 g — potassium salt 10 g per 10 l of water.

3. 1 part of poultry manure (chicken, pigeon) dissolved in 12 parts of water — superphosphate 10 g dissolved in 10 l of water.

4. 1 part of cow manure dissolved in 5 parts of water — superphosphate 20 g per 10 l of the mixture.

5. 1 part of liquid manure to 3 parts of water — superphosphate 20 g per 1 bucket of the mixture.

Information about which crops to fertilize and how much fertilizer to apply in the form of top dressing via irrigation will be provided below.

Knowing the requirements of plants for light, heat, humidity, etc., one can create a schedule for using hotbeds for growing individual crops and a schedule for crop rotation.

The calculation of sowing by crop types and the number of frames occupied by each crop is based on the planned target for each farm. It is the duty of vegetable growers to organize the use of hotbeds in such a way as to fully ensure the fulfillment of the planned target both in terms of growing crops and in delivering produce by the established deadlines. At the same time, all requirements of agrotechnics must be observed when growing individual crops to achieve maximum yield and provide the cheapest possible produce from protected ground.

By using the entire complex of agrotechnics, it is necessary first of all to shorten the growing season of individual crops and, in addition, to lengthen the season of hotbed usage. Stakhanovite vegetable growers begin using early hotbeds as early as January and finish no earlier than November. Their hotbeds are "empty" for only 1–2 months a year and provide a minimum of 2–3 frame turnovers, i.e., they grow vegetables in each hotbed 2–3 times. This is in addition to growing transplants. When using hotbeds in the autumn for final ripening (for example, cauliflower or ripening tomatoes, etc.), a fourth turnover is obtained.

Take, for example, Comrade O. A. Drobenyuk from the Petroraisovet state farm. He has 3,260 frames on his plot and for two consecutive years has received an average of 19.3 kg from each frame, plus 250 transplants per frame. In the first frame turnover, he sowed cucumbers, green onions, carrots, summer squash, radish, and spinach. In the second frame turnover, after the forcing of green onions in February, he used part of the hotbeds for tomato transplants, and the rest for cucumbers, whose transplants he grew in a greenhouse. After planting the tomato transplants into the open ground, the hotbeds were occupied by cucumbers.

The brigade leader of the "Verny Put" collective farm, Comrade S. M. Shcherbakov, received 26.7 kg of early greens per frame in 1938. He applied the following frame turnover. In the first turnover, he grew green onions and radishes. In the second turnover, he sowed cucumbers and, for transplants, late and early cabbage cultivars, leeks, celery, and tomatoes for production (by the second half of July, ripe tomatoes had already gone on sale). In the third turnover, after planting the transplants into the open ground, he occupied the hotbeds with cucumbers.

If comrades Drobenyuk and Shcherbakov had used the hotbeds in the autumn to finish ripening cauliflower or force greens from the roots of parsley, celery, beet, etc., it would have been the most complete use of the hotbeds in four frame turnovers.

In general, the following frame rotation patterns can be recommended for early Russian hotbeds using biofuel, depending on the farm's production targets:

Cucumbers as transplants grown in a greenhouse. Finishing cauliflower

Transplants of tomatoes (pricking out of seedlings from a greenhouse). Cucumbers

Parsley for leaves from roots harvested in autumn in open soil

In medium-sized (transplant-vegetable) hotbeds, the first rotation usually begins with the cultivation of transplants. After forcing transplants, the second rotation consists of sowing cucumbers, zucchini, pumpkin, or tomatoes from transplants grown in a greenhouse or in early hotbeds. Intercropping is possible with the cucumber crop.

Maximum utilization of protected ground allows for fresh vegetables to be obtained during the off-season, when supplies from open soil cease. To ensure that greenhouses and hotbeds do not stand idle, the production cycle begins at the end of winter and concludes at the end of the year. Rational planning of frame rotations helps to utilize the usable area of the structures almost continuously.

• Start of work in hotbeds — January – February
• End of the season — November – December
• Finishing period for cauliflower — September – October

Frame rotation schemes for full utilization of hotbeds and seedbeds

To use areas continuously, established schemes of crop rotation are applied. The choice of scheme depends on the type of protected ground and the growing periods. In practice, two main options for crop distribution have proven effective.

• In medium hotbeds: after harvesting cucumbers in September-October, cauliflower is planted for finishing, using additional insulation.
• In seedbeds (first rotation): transplants of beet, swede, and medium-maturing cabbage cultivars are grown.
• In seedbeds (second rotation): after the area is cleared, cucumbers are planted, as well as cauliflower, the transplants of which were previously grown in early hotbeds.