Detailed Explanation of Key Techniques for Winter Yellow Chive Cultivation
Yellow chive cultivation is a method in which Chinese chives are grown in the open field to build up root reserves, and after the nutrients return to the roots through multiple frosts in the later stage, the chive roots are moved in winter into chive trenches, sunny cold frames and other protective facilities, where the stored nutrients are used under low-light conditions to produce fresh yellow chives.
?I. Preparation of the Chive Trench Choose a plot that is sheltered from the wind, sunny, flat and high and dry (a courtyard will also do), and dig a trench running east-west, 3-4 m wide and 1.25 m deep; the length can be determined by how many chive roots there are, generally 12 m, divided into 7 small beds. The soil layer at the bottom of the trench must both retain moisture and drain well; smooth the four walls of the trench, and make the southern side of the bottom slightly higher than the northern side to facilitate watering. After digging, add a roof cover on the northern side, half the width of the trench, to favour light capture. Spread a 10-13 cm thick layer of corn stalks on the roof, then cover with soil and plaster with mud; the front edge should be 33 cm above the ground, forming a sloped roof high in the south and low in the north, and immediately cover it with straw mats.
????II. Putting the Chive Roots into the Trench
1. Bundling. From after the Start of Winter to before Light Snow, clear away the dead leaves, dig up and sort the chive roots, remove insect-damaged and diseased roots, select healthy roots, align the upper ends of the stem discs, and tie them into square bundles.
2. Putting them into the trench. Place the bundled chive roots tightly on the bottom of the trench, and fill and pack the gaps firmly with loose roots. Build soil ridges between each small bed to prevent water from flowing between them during watering.
3. Water channel setup and watering. On the south side of the bed, three tiles can be arranged into a U-shaped water channel leading into the trench, so that the mats need not be lifted when watering. Generally, the roots are put into the trench after Light Snow, and then a light watering is given, with the water depth at 1/3 the height of the chive roots, and the bed ridges are trampled firm. After 1-2 days, give another heavy watering, with the water depth just enough to submerge the chive roots. After the water seeps in, evenly scatter decomposed, finely crushed horse manure over the chive roots to a thickness of 10-13 cm, pat it firm with a spade, then cover with dry chive leaves, millet straw, wheat straw, etc. to a thickness of 10-13 cm, with the covering slightly thicker around the edges, so that the chive roots sprout evenly. Finally, cover the trench opening tightly with straw mats.
?III. Management of the Chive Trench When the yellow chives have grown to a certain height, the manure must be removed from the field, and management before and after removing the manure must be strengthened.
1. Before removing the manure. After the roots are put into the trench, generally no watering is done, in order to raise the temperature. Lift the mats during the day and cover them at night. After lifting the mats, cover with a layer of reed matting to prevent cold wind from entering. After 4-5 days, control the temperature of the horse manure fermentation at 35°C-40°C; if the temperature is too high, remove some of the covering. The covering in the middle and around the edges can also be swapped to keep the temperature in the bed uniform. After about 10-12 days, when the sprouts are 5-6 cm high, the temperature will rise rapidly, and it must be strictly controlled below 48°C, and all the covering should be removed successively. When removing the manure, use a wooden rake to rake it out, taking care not to damage the sprouts.
2. After removing the manure. First give a light watering, keep the mats covered all day for 2-3 days, and thereafter lengthen the uncovering time from short to long, from 2 hours a day to 6-7 hours, and be sure to cover the mats on cloudy and rainy days. The time for covering the mats each afternoon should be when the chive leaves begin to freeze. The time for watering should be when there are no dew drops on the leaves at the morning uncovering and the leaves are slightly wilted by noon, but the amount of water should not be too large, to prevent leaf rot, watering once every 5-6 days. IV. Harvesting and Post-harvest Management 30-40 days after the roots are put into the trench, that is, about 20 days after removing the manure, harvest the first crop. When harvesting, first set up a wooden board over the trench, stand on the board, and harvest 1 cm above the stem disc, taking care not to damage the stem disc; the first crop yields about 100 kg per bed, the second crop 50 kg, and the third crop 25 kg. After the first crop is harvested, sun them by day and cover them by night for 2-3 days, then cover them day and night for 3-5 days; thereafter the management is the same as for the first crop, except that a small amount of chemical fertilizer can be applied with the watering. After harvesting 3-4 crops, by around the Spring Equinox, dig out the chive roots and plant them in the open field in furrows with a row spacing of 23-26 cm, with a plant spacing of 1-2 cm and a depth such that the chive roots are 1-2 cm below the ground surface, then firm the soil after planting. Around Light Snow, dig up the roots again and put them into the trench; this can be continued for 2-3 years.