Careful management of cotton at the seedling stage can yield twice the result with half the effort
On May 25, at the invitation of the Guangzong Service Station of the Cotton Committee of the China Agricultural Technology Association, I went to Gaojiazhuang, Fengjiazhai Township, Guangzong, to look at cotton fields and talk with farmers about current management techniques. Guangzong County borders Wei County and lies in the rain-scarce, drought-prone zone of south-central Hebei. With mostly sandy soil, it is very well suited to growing cotton and is one of the key cotton-producing counties. At present the seedlings are growing well, with 4 true leaves already showing and thinning just beginning; there is basically no disease. Some plants near trees are damaged by cotton mirids, and a few cotton seedlings have cotton aphids, which the villagers have already treated. Because both equal-row spacing and wide-narrow row spacing were used, cotton field densities vary greatly. Where equal-row spacing is too wide, density is less than 2000 plants; where row and plant spacing is small, density reaches as high as 5000 plants. Overall, the management of cotton at the seedling stage is not taken seriously enough, there is little labor for field operations, and most cotton fields are in a compacted state. The most urgent task now is inter-row cultivation to encourage roots to grow downward; the second is to earth up around the cotton seedlings to preserve soil moisture and raise temperature. When talking with the farmers, I combined the village's actual situation, stressed the importance of cultivation, and explained several management techniques, which the farmers said they understood and agreed with.
1. Cultivation This spring the soil moisture was good, but due to recent high temperatures, frequent wind, and dry weather, the soil has lost moisture severely. Cultivation can cut the soil capillaries and stop further evaporation. In mid-to-late June the north is prone to drought, and soil moisture will be the most scarce resource. Emphasizing moisture preservation at the seedling stage can ease drought stress at the bud stage. Cultivation also encourages roots to grow downward, strengthens the root system, and helps prevent disease. Cultivation should be done after every rain. Cultivation has another advantage: when watering is needed, whether making beds or opening furrows, soil is available; if the field is one hard, compacted expanse, it will inevitably require flood irrigation, which both wastes water and is bad for cotton.
2. Earthing up Many cotton fields still have not earthed up around the cotton seedlings. This should be done immediately, using fine soil to cover the cotton seedlings tightly. At present the main factor limiting cotton seedling growth is soil temperature. Although daytime temperatures are high, nighttime temperatures are low. Earthing up can both raise nighttime soil temperature and reduce soil moisture loss; it can also stabilize the cotton seedlings and prevent them from being shaken by wind. Practice has also shown that this year, wherever earthing up was done in time, it helped the seedlings improve.
3. Do not remove the plastic film early Some farmers, disliking the slow growth of the seedlings, suggest removing the plastic film early and thoroughly ventilating and clearing the ridges. This is not advisable. Practice has repeatedly shown that in May the plastic film must absolutely not be removed. Depending on temperature and the growth condition of the cotton seedlings, the earliest the film should be removed is after June 10. Removing the film now, when nighttime temperatures are low, is even less helpful for the cotton seedlings to improve; when cotton seedlings go from being covered by film to suddenly being exposed, if rain and cooling occur, they are more susceptible to disease.
4. For dense seedlings, apply appropriate early chemical regulation If late seedlings are too dense and soil moisture is also good, high temperatures make excessive vegetative growth very likely. To avoid forming tall, long-jointed, large-leaved seedlings, begin chemical regulation from the end of May to early June, spraying about 0.2 grams of mepiquat chloride per mu to promote strong, steady growth and balanced growth of aboveground and belowground parts.
5. For sparse seedlings, keep strong leafy branches In cotton fields with low density, keep 1 to 2 strong leafy branches per plant to make up for the shortage of plant numbers. Never remove all leafy branches by "rolling up the trouser legs" too early.
This year cotton planting is not like usual, because the expected price of new cotton is high, making this a rare high-benefit year in many years. What should be invested must be invested, and the returns will increase severalfold or even more. Management at the seedling stage can especially achieve twice the result with half the effort.