Detailed Explanation of Potato Cultivation Technology with Rice Straw Mulching

In 2000, Zhejiang Province carried out research on a new technique for no-till rice paddy cultivation of potatoes with full rice straw mulching, changing "planting seed potatoes" to "placing seed potatoes" and "digging potatoes" to "picking potatoes." The whole process can be vividly summarized as "place, cover, pick," eliminating many operations such as plowing and land preparation, digging holes for planting, intertillage weeding, and digging potatoes. The fresh potato yield per 667 sq m was over 1500 kg. A few years ago, our province introduced this technique and demonstrated it successfully.

1. Select good varieties. Varieties suitable for planting in our province include: the extra-early-maturing variety Dongnong 303, the early-maturing variety Kexin No. 4, the mid-maturing varieties Nanzhong 552 and E Potato No. 3, and processing-type varieties such as Atlantic.

2. Field selection and bed preparation. It is advisable to choose rice paddy fields with deep topsoil, fertile and loose soil, good drainage and irrigation, rich organic matter, neutral or slightly acidic soil, and a sandy texture. When harvesting rice, the rice stubble should not be too low or too high; leaving stubble 15 cm to 20 cm high is best. Before sowing, first divide the field into beds and open furrows. The bed width is 1.4 m to 1.6 m, the furrow width is 20 cm to 30 cm, and the furrow depth is 15 cm to 20 cm. The soil dug out when opening furrows should be evenly thrown onto the middle of the bed, and the bed surface should be shaped into a turtle-back form to facilitate drainage. Large weeds in the field can be removed manually; herbicides must not be applied.

3. Seed potato treatment. Select fresh seed potatoes that are free of pests and diseases and frost damage, with smooth skin. It is best to use whole seed potatoes weighing about 30 g each; their sprouting vigor, seedling growth rate, and yield are all better than those of cut seed potatoes. However, in production there are often seed potatoes weighing more than 50 g each. These seed potatoes need to be cut with a knife, and each cut piece must have one or two bud eyes with apical dominance; otherwise, they will not sprout after sowing or will grow very weakly. If rotten potatoes are encountered, the knife must be cleaned before continuing to cut. Soak the cut potato pieces in a carbendazim solution for 3 minutes to 5 minutes, remove them, spread them out to air-dry the surface moisture, and mix the seed pieces with plant ash to prevent the cut surfaces from becoming infected and rotting. When sowing, do not knock off the sprouts on the seed potatoes. Seed potatoes that have not yet passed the dormant period need to be sprouted to break dormancy, promote early sprouting, early emergence, and uniform emergence.

4. Timely sowing. In the Changsha area, spring potatoes are sown around the Spring Festival (mid-to-late December to January of the following year), and autumn potatoes are sown around End of Heat (late August). Other areas can sow appropriately earlier or later according to latitude and altitude. Place the treated seed potatoes directly on the bed surface. Generally, four to five rows are placed per bed, with a row spacing of 35 cm and a plant spacing of 25 cm, sowing 4500 to 5500 plants per 667 sq m. When sowing, press the seed potatoes down slightly with a little force so that the bud eyes are in full contact with the soil.

5. Fertilization and straw covering. After sowing, cover the seed with ash fertilizer (plant ash, coal ash, burnt soil ash) mixed with 1500 kg of decomposed pig manure, preferably enough to cover the seed potatoes. Then broadcast 30 kg to 40 kg of compound fertilizer per 667 sq m on the bed surface, and then evenly cover with rice straw 8 cm to 10 cm thick. (Rice straw that is scattered after mechanical rice harvesting is not suitable for mulching, as it will prevent potatoes from emerging.) If drought occurs when covering with straw, the straw should be moistened with water; if strong winds occur, branches should be used to press down the straw to prevent the wind from blowing it up. After covering with straw, clean the furrows and evenly press the soil dug from the furrows onto the straw to prevent the straw from being blown away by strong winds and exposing the seed potatoes.

6. Water management. During the growth and development period of autumn potatoes, sufficient water must be ensured, especially during the tuber bulking stage, when aboveground transpiration is vigorous and underground stems grow rapidly. At this time, water demand is greatest, and the soil should remain moist regularly to promote tuber expansion and also help the rice straw decompose. During drought, irrigate with a small amount of water along the furrows so that the water slowly seeps into the beds; do not use large-scale flooding irrigation. In years with abundant autumn rain or in low-lying areas, attention should be paid to drainage to prevent waterlogging. After the beginning of spring, even more attention should be paid to timely cleaning of furrows and draining of water.

7. Timely harvest. When the stems and leaves turn yellow, which indicates that the tubers are mature, they can be harvested. For small-scale household planting in rural areas, the large tubers can be harvested first, leaving the small tubers in the field to continue growing. When potatoes are grown with rice straw mulching, 70% of the tubers grow on the ground surface, and very few tubers enter the soil. At harvest, simply push aside the rice straw and pick up the potatoes.