When to Sow Winter Potatoes? Detailed Field Management Methods

After the late rice harvest, some farmers begin using idle winter fields to grow potatoes, harvesting and selling them in February-March of the following year before potatoes hit the market in large quantities, which can bring considerable profit. So when is the best time to sow winter potatoes? How should field management be done?

I. When is the best time to sow winter potatoes?

Planting should be done immediately after the late rice is harvested, with late October to early November being the most ideal. Note that if paddy fields are converted to potato cultivation, it is best to plant in deep furrows with high ridges; heavy, clayey paddy soil prone to compaction should not be chosen. To prevent the spread of disease, avoid continuous cropping with solanaceous crops such as peanuts, tobacco and tomatoes.

In addition, choosing fertile sandy soil with convenient drainage and irrigation and sowing early at the right time is the foundation for achieving high yield and quality.

II. How should field management be done for winter potatoes?

1. Water management

Potatoes are a crop with high water demand. Soil water deficiency reduces the plant's absorption rate of nutrients such as N, P and K, and reduces dry matter accumulation in the tubers. Most of the growth period of winter potatoes falls in the dry season with little rain and low air humidity, especially the driest season from February to April each year, which is precisely when potatoes grow most vigorously and have the greatest demand for water, and is also the key period determining yield. In February-March, it is best to water once a week. Throughout the whole growth period of potatoes, keeping soil moisture at 60%-80% of the maximum field water-holding capacity is most suitable.

2. Nutrient management

(1) The basic principle of fertilization is to combine organic and inorganic fertilizers, with basal fertilizer as the main application and topdressing as a supplement, balancing fertilization to achieve early promotion, mid-term control and late-stage maintenance. In the early stage, potatoes should be encouraged to germinate early and grow quickly with many branches; fertilization should focus on nitrogen, phosphorus and potassium, with 70% of the fertilizer applied within 60 days after emergence. In the mid-term, control stem and leaf growth to prevent excessive vegetative growth and promote the transition to tuber formation and expansion underground. In the late stage, leaf color should not turn yellow too early, so as to maintain leaf photosynthetic efficiency and produce more nutrients for underground tuber expansion; fertilization should focus on potassium and calcium fertilizers, with appropriate supplemental nitrogen. All fertilizer should be applied within 30 days before harvest.

(2) Application of basal fertilizer: organic fertilizer should be applied at sowing, with 30-40 tonnes of fully decomposed organic fertilizer per hectare, 900 kg per hectare of 45% potato-specific compound fertilizer (13-6-16, with medium and trace elements) or compound fertilizer, 300 kg of superphosphate, 150 kg of urea and 300 kg of potassium sulfate.

(3) Application of topdressing: topdressing is mainly nitrogen, phosphorus and potassium fertilizers, but the application time should not be too late, especially in the late stage, to avoid excessive stem and leaf growth and to avoid affecting tuber expansion and quality. Topdressing should be applied at about 250 kg per hectare of Jiamei Yinglilai in 2-3 split applications. The first topdressing is carried out when seedlings are fully emerged, applied with water to promote early growth and increase the photosynthetic area. The second topdressing is carried out at the budding stage to promote continued stem and leaf growth, increase the photosynthetic area and benefit tuber expansion. Topdressing is best done in the afternoon, and fertilizer should be prevented from touching the leaves; if fertilizer is broadcast, water should be applied immediately to speed up dissolution and also to wash the leaves. During the tuber expansion stage, spray Jiamei Brain Platinum at 800 times dilution 2-3 times.

3. Intertillage weeding and ridging

The tuber-bearing layer of potatoes is mainly distributed in the 10-15 cm soil layer, requiring a loose soil environment. To create a good environment for healthy plant growth and tuber expansion, intertillage weeding is usually carried out 3 times: the first time after seedlings are fully emerged and before row closure, with appropriately deep hoeing; the second and third times with shallow hoeing to prevent cutting the newly grown stolons. Combine each intertillage weeding with ridging and earthing up. Early and timely earthing up causes no damage to underground roots and stems, and high earthing up helps retain water and fertilizer, prevent frost damage, reduce green tubers, improve tuber quality and increase yield.

4. Pest and disease control

(1) Principles of control: to obtain higher yield and quality, pests need to be strictly controlled, especially aphids and others that can transmit viruses; aphid control starts from emergence. Do not use pesticides banned by the state for high toxicity, high residue, high bioaccumulation or high three-cause effects (teratogenic, carcinogenic, mutagenic) or their mixed pesticides.

(2) Chemical control of insect pests: aphids can be controlled with 2.5% bifenthrin emulsifiable concentrate or 10% imidacloprid wettable powder. For underground pests such as mole crickets and cutworms, chlorpyrifos and other pesticides can be used for trapping and killing; for above-ground leafminers and cabbage caterpillars, pesticides such as Banqianjing can be used for control.

(3) Chemical control of diseases: diseases in winter potato cultivation are relatively mild, but for the main winter potato diseases such as bacterial wilt, late blight and leafroll virus disease, timely spraying should be carried out, and diseased plants should be pulled out promptly. In areas where late blight is severe, pesticides such as metalaxyl mancozeb, ridomil and Infinito should be used to control late blight; usually 2-3 sprays can achieve the control effect.