Key Technical Points for Water-Saving Cultivation of Wheat and Foxtail Millet with Two Crops a Year
In the two-crops-a-year region of the low plains of our province, the main wheat planting pattern is wheat + corn. In recent years, the benefits of this planting pattern have become increasingly low. Under the current overall environment of groundwater extraction reduction, the wheat planting area will decrease somewhat, but the habit of wheat as the staple food of northern people will still exist for a long time. Therefore, exploring efficient cultivation patterns with wheat as the preceding crop is still of great significance.
The maturity period of winter wheat in our province is mostly in early to mid-June. At this time, it is exactly the best sowing period for summer foxtail millet. More importantly, foxtail millet is drought-tolerant. Apart from needing one irrigation before sowing to build soil moisture, it can usually rely on summer rainfall throughout the entire growth period. It saves at least one irrigation compared with corn, and the market price of foxtail millet is 2 to 3 times that of corn. In recent years, foxtail millet has developed into a simplified and efficient mechanized production model. Practice shows that, based on a yield of 300 kg of foxtail millet per mu and converted at current market prices, the "wheat + foxtail millet" planting pattern earns 300 to 500 yuan more per mu than the "wheat + corn" pattern or the one-crop-a-year cotton planting pattern.
I. Water-Saving Cultivation Technology for the Preceding Wheat Crop
1. Improve land preparation quality, apply fertilizer scientifically, and build soil moisture. Before rotary tillage of the plot, crush the straw of the preceding crop twice, with stem segments 3 to 5 cm long, spread evenly, and apply basal fertilizer. Adopt the fertilization strategy of stabilizing nitrogen, increasing phosphorus, supplementing potassium, and matching micronutrients. Generally, apply 40 to 50 kg of ammonium bicarbonate, 75 to 100 kg of calcium superphosphate, 5 to 10 kg of potassium sulfate, and 1 to 2 kg of zinc sulfate per mu, or 25 kg of diammonium phosphate, 10 to 20 kg of urea, 5 to 10 kg of potassium chloride, and 1 to 2 kg of zinc sulfate as basal fertilizer. In plots with straw returned to the field, a certain amount of quick-acting nitrogen fertilizer must be ensured in the basal fertilizer.
Sufficient bottom soil moisture is a key measure for achieving water-saving and high yield and ensuring robust spring growth. Generally, sowing by seizing available soil moisture is not recommended, because after seedling emergence from sowing by seizing available soil moisture, if there is little rainfall before winter, winter irrigation will inevitably have to be applied, which will lead to soil hardening, cracking, rapid evaporation, and many dead seedlings over winter. Therefore, wherever there is no effective rainfall of more than 50 mm before sowing, sufficient bottom soil moisture water should be applied, with an irrigation amount of 50 cubic meters per mu. For those sown later, the sowing quality must be ensured even more: first irrigate to build bottom soil moisture, then prepare the land and sow, avoiding winter irrigation.
2. Sow late at the appropriate time, match sowing rate, and ensure sowing quality. Late sowing at the appropriate time can reduce water evaporation loss. In addition to leaving sufficient maturity time for the summer foxtail millet crop, it also helps robust growth before winter, safe overwintering, and is conducive to the planning of wheat water-saving technology. Within the suitable sowing period, there must also be a suitable sowing rate. For sowing from October 5 to 10, the general sowing rate is about 12.5 kg per mu; for sowing from October 10 to 15, the sowing rate is about 15 kg per mu. For late sowing, increase the sowing rate by 0.5 kg for each day delayed.
Sowing quality is the key to ensuring water-saving and high-yield wheat cultivation. Requirements: carefully select seeds, do a good job in seed treatment, ensure accurate sowing rate, adopt equal row spacing of about 14.5 cm, and strive for consistent sowing depth (sowing depth 4 to 5 cm) with uniform seed drop. Pay attention to timely compaction during sowing. After sowing, build ridges and make beds. Small-bed irrigation can reduce the irrigation amount, and making about 12 beds per mu is appropriate.
3. Promptly check and replant seedlings, improve planting quality, and simplify winter management. Check and replant seedlings 10 to 15 days after sowing. If rain occurs before seedling emergence, promptly hoe and loosen the soil to break up hardening. Under a series of conditions that improve sowing technology, such as sowing with sufficient soil moisture, straw crushing and returning to the field, good land preparation quality, suitable sowing period and sowing rate, and compaction after sowing, generally no freezing irrigation is applied. Where freezing irrigation is needed, it should be applied after the temperature steadily drops to about 3°C, generally from the end of November to the beginning of December. Where bottom soil moisture water was not applied for various reasons, freezing irrigation must be ensured before overwintering if there is no major effective rainfall.
4. Irrigation, fertilization, and weed control: spring management is key. The period from wheat greening to heading is the spring management period for wheat, mainly irrigation, fertilization, and weed control. For irrigation, pay attention to appropriately delaying the first spring irrigation time. After adopting the above technical measures to improve planting quality, irrigation should generally be delayed until the jointing stage, that is, April 5 to 10 of the second year, and no later than April 15. Each irrigation amount is 45 to 50 cubic meters; at the same time, nitrogen fertilizer is topdressed with the first irrigation. Generally, about 20 kg of urea is applied per mu.
After wheat greening, pay attention to timely weed control. Tribenuron-methyl herbicides can be used, and 2,4-D herbicides should be avoided as much as possible to ensure safety to wheat. In addition, note that the timing of application should be appropriate. If applied too late, the dosage is large, the cost is high, the control effect is poor, and it is also likely to cause wheat phytotoxicity. Tribenuron-methyl wheat field herbicides generally have a better weed control effect when the temperature is above 10°C. For plots where the first spring irrigation is delayed to early April, spraying herbicides from March 20 to 25 is generally better. Generally, 10 g per mu of 10% tribenuron-methyl can be sprayed evenly.
5. Strengthen late-stage management, focus on disease and pest control, and prevent dry hot wind. The period from wheat heading to maturity is the late-stage management period. During this period, pay attention to irrigation, disease and pest control, and prevention of dry hot wind. After the first wheat irrigation is delayed, in ordinary years one more irrigation at the early grain-filling stage after wheat flowering is sufficient. This period is when light penetration in the wheat field is poorest, so pay close attention to inspection and control of wheat powdery mildew and leaf rust. In wheat disease control, pay attention to timely and continuous application. When disease occurs in spots and patches, use fungicides such as triadimefon for two applications, with an interval of 1 week between the two applications. The control threshold for wheat aphids is 800 aphids per hundred plants. For convenience of inspection, early control can be carried out when wheat aphids are found on the flag leaf. It is better to be early than late, and attention should be paid to using high-efficiency and low-toxicity pesticides. Generally, pirimicarb or imidacloprid can be used for 1 to 2 applications. Generally, the first application uses a systemic pesticide, and the second uses a contact-killing pesticide.
In addition to the above conventional diseases and pests, the following two diseases and pests occur increasingly seriously year by year in this region, so pay attention to their control: 1) Wheat blossom midge. First, do a good job in monitoring. For plots where each sampling point (in soil 10 cm long, 10 cm wide, and 20 cm deep) has more than 5 insects, chemical control should be carried out. Adopt a control strategy based mainly on control during the pupal stage and supplemented by control during the adult stage. Pupal-stage control is carried out 3 to 5 days before wheat heading. Pesticides used: chlorpyrifos or isofenphos-methyl granules mixed with 20 to 25 kg of fine soil, scattered along the rows in the wheat field. After scattering, hoeing and irrigation can improve the control effect. During the adult stage, when wheat is heading and flowering, a mixed solution of pyrethroids and dichlorvos can be used for whole-field spraying. 2) Wheat scab. When rain occurs during the wheat heading and flowering period, wheat scab generally occurs more seriously. Broad-spectrum fungicides such as diniconazole or carbendazim can be used for spraying, twice continuously, with an interval of 5 to 10 days.