Planting methods and timing for Lipu taro: sow after the last frost

SummarySoil preparation: it is best to plant in fertile, loose soil with convenient drainage and irrigation, in a field where taro has not been grown before, and to apply an appropriate amount of organic fertilizer as base fertilizer. Mulching and close planting: after the winter solstice, mulching is needed to promote sprouting, and close planting uses a wide-and-narrow row cultivation method. Ditching and mulching: dig ditches according to the wide row spacing, after ridging level it slightly, spray herbicide, then cover with transparent plastic film. Fertilization and water management: fertilize reasonably and manage water scientifically. Intertillage and hilling: before the rows close, combine intertillage, weed control, and hilling 2-3 times. Manual weeding: carry out manual weeding at the appropriate time.

1. Fine soil preparation and sufficient base fertilizer

1. Field selection and soil preparation

(1) Taro has a well-developed root system. The part we generally eat is the underground corm of taro. It is suitable for planting in fertile, loose fields that retain fertilizer and water, have convenient drainage and irrigation, and where taro has not been grown in the previous year.

(2) When planting, continuous cropping should be avoided. One year of continuous cropping can cause a yield reduction. For example, after continuous cropping with corn and other grass-family crops, yield can decrease by 30%. The previous crop is best sweet potato or peanut.

(3) Prepare the soil before sowing and plow deeper than 40cm, which is beneficial for corm growth and increasing yield.

2. Apply sufficient base fertilizer

(1) Apply about 2500kg of organic fertilizer as base fertilizer per mu, or apply 6000kg of farmyard manure with high organic matter content, then plow deeply after fertilizing.

(2) When fertilizing, the ratio of nitrogen, phosphorus, and potassium is 1.2:1:2 respectively. For every 100kg of corms produced, 1-1.2kg of pure nitrogen, 0.8-0.84kg of phosphorus pentoxide, and 1.6-1.68kg of potassium oxide are needed.

(3) The amount of chemical fertilizer is based on diammonium phosphate 35kg/mu, compound fertilizer 50kg/mu, bone meal 100kg/mu, and ammonium bicarbonate 75kg/mu.

(4) Around mid-July, apply appropriate fertilizer, topdressing an appropriate amount of phosphorus and potassium fertilizers such as potassium sulfate and superphosphate, as well as ammonium bicarbonate and diammonium phosphate.

(5) As seed fertilizer, apply 25kg/mu potassium sulfate compound fertilizer and 50kg/mu superphosphate.

2. Early sowing with mulching and reasonable close planting

1. Sowing and mulching

(1) Sowing time

Taro likes warmth and fears frost, so it is generally sown after the last frost. If sown too early, low soil temperature can easily cause seed rot or weak seedlings; if too late, high soil temperature can easily burn seedlings. This can be controlled according to actual conditions. For example, after taro emerges and is not damaged by freezing, the sowing period should be early. Advancing the planting time can extend the taro growth period and achieve increased yield, and taro has a long growth period. It germinates when the temperature exceeds 13-15°C. Planting time is usually in early to mid-March, and plastic film cultivation can be advanced by one month.

(2) Mulching to promote sprouting

After the winter solstice and before New Year's Day, cover with film to promote sprouting. This not only increases temperature and preserves moisture, but can also increase yield by 38.5%-50%, increase the proportion of daughter taro and the finished product rate, and allow sowing about one month earlier than open-field cultivation. After roots grow and buds sprout, around January, plant taro on sunny days, and it can be harvested before mid-August.

2. Seed selection

Research shows that sowing 20g seed taro reduces yield by more than 13% compared with 50g seed taro. In addition, for seed taro of the same size, cutting the stem reduces yield by more than 6% compared with uncut whole taro. Therefore, in production, medium-sized daughter taro should be selected as seed, as it contains more nutrients and is beneficial for plant growth.

At the same time, choose corms without wounds and without disease, insect, or mold rot, with the apical bud tip well preserved, weighing about 50g and round in shape, as the best. In addition, when selecting daughter taro from the middle part of taro as seed, the seed taro hairs and side buds should be removed to prevent side buds from sprouting.

3. Sunning seed and promoting sprouting

15-20 days before sowing, sun the seed and promote sprouting, such as with moist sand. First dry the stored taro in the sun for 1-2 days, place the seed taro separately in a sprouting bed, keep the temperature at 18-20°C, and sow when the buds are about 1cm long. This can ensure uniform emergence of taro.

4. Reasonable close planting

(1) Sow using a wide-and-narrow row cultivation method, with plant spacing of about 27-33cm, wide row spacing of about 60cm, and narrow row spacing of about 30cm for close planting.

(2) Taro can be planted at about 4500-6000 plants per mu, which can produce reasonable economic benefits. Of course, planting density should also depend on the variety, soil, and water and fertilizer conditions. Generally, the better the planting conditions, the denser the planting.

3. Ditching, ridging, mulching, and deep burying

1. Ditching

Dig ditches 10cm deep and 35cm wide according to the wide row spacing, irrigate the ditches to create suitable soil moisture, place seeds in a triangular staggered pattern with bud tips facing up, apply an appropriate amount of chemical fertilizer, and apply 15-20 grains of cooked soybean containing phoxim as seed fertilizer to prevent insect pests.

2. Ridging

Form ridges about 20cm high and 50-60cm wide, level slightly, then cover the seed taro with about 12cm of thick soil. After autumn, there is no need to divide ridges and cover soil again, and few or no green-headed taro will appear, increasing yield without damaging roots and improving taro quality.

3. Mulching

After spraying herbicide, choose 7-8 jin of transparent plastic film for covering. When mulching, the bed surface should be flat, the soil fine and crumbly, and the edges pressed tightly with soil. It can be retained until late June to early July. Remove the film when topdressing. After covering, check carefully. After emergence, break the film and seal the holes with soil so the crop can grow and develop normally. If missing seedlings are found, replant them in time.

4. Reasonable fertilization and scientific water management

1. Reasonable fertilization

(1) Early seedling stage: apply seedling-promoting fertilizer once, and apply topdressing 2-3 times during the early and middle stages of vigorous growth and corm growth. Note that nitrogen, phosphorus, and potassium fertilizers should be applied together, with less fertilizer earlier and more later.

(2) Late seedling stage: to prevent excessive vegetative growth and late maturity, control the amount of topdressing. According to a nitrogen-phosphorus-potassium ratio of 15:15:15, apply 40-50kg/mu compound fertilizer as base fertilizer, plus 100-150kg ordinary calcium superphosphate.

(3) After seedlings are uniform: according to a nitrogen-phosphorus-potassium ratio of 16:10:20, topdress 75-100kg/mu compound fertilizer, apply the fertilizer mixed with water, and during this period combine with hoeing weeds, hilling, and mulching.

(4) Early June at the 3-4 leaf stage: at this time taro begins to expand. Mix 1000kg/mu farmyard manure, 15kg/mu potassium sulfate, 50kg/mu bio-organic fertilizer, and 2kg/mu boron-zinc-magnesium fertilizer, compost for 30-45d, then apply fertilizer and cover with soil.

(5) June-July expansion period: during pest and disease occurrence, spray expansion agent plus potassium dihydrogen phosphate, etc.

(6) Mid-July, 5-6 leaf stage before Major Heat: after pulling weeds, mix and apply 25kg/mu potassium sulfate compound fertilizer and 15kg/mu potassium sulfate, then cover with a layer of shallow soil.

(7) After August: stop fertilizing.

2. Scientific water management

1. Taro likes water and fears drought and waterlogging. Its leaves are large and its water demand is high. Avoid dry soil, which can easily cause yellowing and withering of leaves.

(1) In the early stage, temperature is low and growth is slow, so only keep the soil moist. Avoid watering at the seedling stage, as it will affect root development and emergence.

(2) In the middle and late stages, temperature is high and growth is rapid, so it is best to irrigate in the morning and evening. Watering at noon in hot seasons can easily cause leaf withering. Before fertilizing and removing the film, keep the bed surface moist. Prevent drought in summer with appropriate watering, and pay attention to drainage in the rainy season.

(3) During the peak growth period, there should be at least about 3cm of water at the bottom of the ditch to keep it moist. Control watering 20d before harvest, and stop irrigation 10d before harvest.

5. Intertillage and hilling

1. Excessive growth of taro corms will affect yield and quality. On one hand, hilling can inhibit the sprouting of the apical buds of daughter taro and grandchild taro; on the other hand, it can reduce nutrient consumption, thereby promoting corm growth.

2. Before the rows close, combine intertillage, weed control, and hilling 2-3 times, once every 15-20 days, covering with 5-7cm of soil each time. Planting with high ridges, mulching, and deep burying does not require hilling.

6. Timely application of chlormequat and removal of daughter taro

1. Apply paclobutrazol and seedling-strengthening agent

(1) When plants have 5-6 leaves and are about 45cm tall, mix and drench with 8kg/mu seedling-strengthening agent and 150g/mu paclobutrazol. After 20d, drench again with 150g/mu paclobutrazol or spray on the leaves.

(2) Increase or decrease the dosage according to plant vigor. It is best to do this on sunny days. Use 15g paclobutrazol plus 40kg water to pour into the heart leaves of 80-100 plants. When plants are 80cm tall and have more than 5 leaves, the rows basically close.

2. Removal of daughter taro

At the 7-8 leaf stage, remove daughter taro, which can concentrate and preserve nutrients and help the mother taro expand. When daughter taro has one leaf and one heart, cut off the growing point. For daughter taro kept for seed, keep 3-4 mother seedlings and do not remove them.

7. Manual weeding

1. After sowing and watering, use pre-emergence herbicide for weed control. Choose Dual, prometryn, etc., or Harnes liquid herbicide 20ml mixed with 60kg/mu water to make a spray and apply over the whole field.

2. You can also use 150g/mu acetochlor herbicide to spray the ground. During the growth period, combine with fertilizing and loosening soil for manual weeding.