Key Technical Points and Management Methods for Winter Seedling Cultivation
November is almost here, which means the north is about to see its first snow. From winter to the return of spring is roughly over a hundred days, so under prolonged low temperatures, how to ensure seedling survival through winter is the key to a good harvest the following year.
An agricultural proverb says: "A thousand waterings are not as good as one application of winter fertilizer." The best time to apply winter fertilizer is 10 to 15 days before the Winter Solstice. Generally, 1200 to 1500 kg of pig and cattle manure per mu, or 2500 to 3000 kg of farmyard manure, can raise soil temperature by 2°C to 3°C, achieving the effect of winter application and spring growth.
???? Watering the freezing water well
Watering the freezing water must meet the "one determination" and "two adequacies." "One determination" means deciding whether to water the freezing water based on the soil moisture content. Generally, when the absolute moisture content of sandy loam is below 15%, loam below 17%, and clay below 20%, freezing water should be applied. "Two adequacies" means watering at the right time and in the right amount. The suitable time for watering freezing water is when the soil plough layer thaws during the day and freezes at night. Watering in the right amount means the amount of freezing water should not be too much or too little. Generally, it is suitable when it connects with the subsoil moisture.
???? Mulching for cold protection
During the severe cold period in northern regions, the absolute low temperatures are very unfavorable for vegetable seedlings to overwinter safely. Therefore, mulching should be used for cold protection to ensure the seedlings overwinter safely. Mulching can generally be carried out after the soil in the plough layer has completely frozen. The mulch can be farmyard manure rich in organic matter that has been broken up and finely crushed.
Apply winter fertilizer well
Applying winter fertilizer can increase soil nutrient content, achieving the effect of winter fertilizer for spring use and promoting weak plants to become strong. This is especially important for vegetable plots with little base fertilizer, poor soil fertility, and weak seedlings. Therefore, winter fertilizer should be applied together with the freezing water, generally 10 kg of urea or 20 kg of ammonium sulfate per mu, applied with the water.
???? Intertillage and earthing up, clearing ditches and draining water
Intertillage and loosening the soil, and earthing up around the roots, can improve the soil environment, regulate soil moisture, raise soil temperature, and also prevent lodging and reduce the harm of weeds and sclerotinia. The depth of intertillage should vary according to growth conditions. Generally, it should be shallow first and then deep. For plots with vigorous growth, shallow hoeing is appropriate. Before overwintering, combine intertillage with earthing up around the roots.
After the cold wave passes, check the seedlings promptly. If root exposure occurs, promptly break up the soil and earth up around the base by 8 to 10 cm to prevent broken roots and dead seedlings; in rainy and snowy weather, drain field water early to avoid waterlogging that hinders root growth; when thawing, spread plant ash and promptly spray the leaf surfaces with clean water to ease water imbalance and prevent water loss and dead seedlings; after thawing, promptly apply quick-acting fertilizer.
Corresponding technical measures should be taken promptly according to local production conditions to prevent or reduce the occurrence of freeze damage and ensure that vegetable seedlings overwinter safely.