A Full Analysis of the Best Time for Corn Sowing and Fertilization Requirements in 2017
Spring corn sown early gives high yields and good economic returns. However, because of early sowing, the soil temperature is often low and unstable, which easily causes seed rot. To ensure that spring corn seedlings are uniform, even and strong, and to achieve the goal of high yield and high efficiency, today we will study issues related to spring corn sowing techniques together. To that end, let us first find out when the best time for spring corn sowing is in various parts of the country in 2017. In view of this timing, distributors should also hurry to stock up!
When is the spring corn sowing time in various parts of the country in 2017?
From south to north, there are regions sowing spring corn from mid-February to early May, and it is generally best to sow when the temperature of the 10cm soil layer is stable above 10°C. The harvest period also runs from south to north, from late July to mid-September, a difference of more than 50 days. Its growth characteristics are slow seedling-stage growth, shorter basal internodes, a low ear position, robust plants, and relatively strong lodging resistance.
Under normal circumstances, corn sowing begins around Guyu (around April 20). The corn sowing period in Northeast China is from late April to early May, and it can be harvested in late August. Autumn corn must be sown no later than mid-July and is harvested in mid-to-late October. The Huang-Huai-Hai region has both spring corn and summer corn; spring corn is also sown at this time, while summer corn is sown after the winter wheat harvest, roughly around June.
The best time for spring corn planting in various regions
Spring corn sowing time in Shandong. Because spring corn is sown early and has a long growth period, its yield is high. In the Shandong region, spring corn is generally planted in early April and harvested at the end of August.
Spring corn sowing time in Northeast China. The sowing time is after Guyu (around April 20) and before May 10, and the harvest is roughly after October 1 and before October 20.
Spring corn sowing time in the South. Corn can be grown for two seasons in the South; in the Yangtze River basin, spring-sown corn is generally sown in late March to early April and can be picked in early to mid-July.
Spring corn sowing time in Hebei. Corn is divided into spring corn and autumn corn; spring corn is sown in late April to early May and can be harvested in late August; autumn corn must be sown no later than mid-July and is harvested in mid-to-late October.
Spring corn sowing time in Anhui. Generally, after the first spring rain arrives, that is the best time to plant spring corn. But now, in order to prevent pest and disease damage, it is advocated that spring corn should be sown somewhat earlier, generally before mid-April.
Spring corn sowing time in Hunan. Spring corn is generally sown in early to mid-April and harvested in early to mid-August. Summer corn is sown from late May to early June and matures in mid-to-late September.
In order for spring corn to have a good harvest, the precautions for spring corn sowing are introduced in detail below:
Precautions for spring corn sowing
1. Soil temperature
For spring sowing, it is generally necessary to ensure that the ground temperature of the 5-10cm topsoil layer is stable above 10°C and the air temperature is stable above 12°C; sowing at this time allows normal germination and emergence.
2. Soil moisture
At sowing, the soil moisture of the plow layer is required to reach 60%-70% of field capacity. Generally speaking, if a handful of plow-layer soil can be formed into a ball and breaks apart naturally when dropped, then the soil water content is generally around 60%-70%, which is suitable for sowing.
If a handful of soil cannot be formed into a ball, then the soil water content is on the low side and is not suitable for sowing; irrigation is needed or sowing must wait for rain.
If a handful of soil forms a ball but does not break apart naturally when dropped and instead remains a clod, then the soil water content is too high, which affects emergence.
3. Sowing depth
Generally 4-5cm is suitable. If the soil is sticky and heavy and the moisture condition is good, it can be slightly shallower. For loose-textured, easily dried sandy soil, it can be slightly deeper, but generally not more than 10cm. Sowing too deep prolongs emergence time, consumes more nutrients, and after emergence the seedlings are weak or cannot emerge and remain curled under the surface; sowing too shallow easily dries out the surface soil and prevents full emergence; uneven sowing depth means some emerge early, while some emerge late or fail to emerge, easily leading to large and small seedlings.
The above is the spring corn sowing time in various parts of the country in 2017, and the precautions for spring corn sowing are introduced in detail here. In different regions and different environments, corn planting times also differ. It is suggested that corn growers in various places choose the corn planting time according to the local environment.
The nutrient requirements of corn throughout its growth period
Corn growth requires the absorption of various mineral nutrient elements from the soil, among which nitrogen is the most, potassium is next, and phosphorus ranks third.
Generally, for every 100 kg of grain produced, it is necessary to absorb 2.5 kg of pure nitrogen, 1.2 kg of phosphorus pentoxide, and 2.0 kg of potassium oxide from the soil. The ratio of nitrogen, phosphorus and potassium is: 1:0.48:0.8.
Fertilizer application amount = (the amount of a certain element required for the planned yield - the amount of that element supplied by the soil) / (the content of that element in the fertilizer (%) × the fertilizer's utilization rate in the current season (%)). The utilization rate of fertilizer varies greatly. According to experiments, the current-season utilization rate of general organic farmyard manure is about 30%, that of nitrogen fertilizer is about 40%-50% (calculated at 40%), and that of phosphorus and potassium fertilizers is about 30%-40% (calculated at 30%).
Question: For a planned yield of 500 kg of corn grain per mu, how much fertilizer needs to be applied? Assume that in the soil survey, the soil nitrogen content is 17 kg per mu, phosphorus pentoxide is 6.0 kg, and potassium oxide is 14.4 kg. The soil nutrient utilization rates are 50% for nitrogen, 70% for phosphorus pentoxide, and 30% for potassium oxide. According to the national fertilizer experiment average of 500 kg per mu, for every 100 kg of grain produced, the requirements are 2.9 kg of nitrogen, 1.2 kg of phosphorus, and 2.4 kg of potassium. Calculate the application amounts of urea, superphosphate and potassium chloride (urea contains 46% available nitrogen, superphosphate contains 16% available phosphorus, and potassium chloride contains 50% available potassium).
Corn fertilizer application amount
1. Determine the target yield
Target yield is the yield to be set for the corn planted that year, and it is determined by the level of soil fertility of the cultivated land. In addition, based on the average corn yield of the plot in the previous 3 years, an increase of 10%-15% can also be used as the target corn yield. For example: a certain plot has relatively high-fertility soil, and the planned corn yield that year is 600 kg. The nitrogen, phosphorus and potassium nutrient amounts required throughout the corn growth period are 15 kg, 7.2 kg and 12 kg respectively.
2. Calculate the soil nutrient supply
Determine how much available nutrient the soil contains, and then calculate how much nutrient is contained in 1 mu of land. For 1 mu of surface soil calculated at 20 cm, there is a total of 150,000 kg of soil. If the measured value of soil alkaline hydrolyzable nitrogen is 120 mg/kg, the measured value of available phosphorus content is 40 mg/kg, and the measured value of available potassium content is 90 mg/kg, then the total amount of available alkaline hydrolyzable nitrogen in 1 mu of soil is: 150,000 kg × 120 mg/kg × 10 to the negative 6th power = 18 kg, the total available phosphorus is 6 kg, and the total available potassium is 13.5 kg.
Because various soil factors affect the availability of soil nutrients, not all available nutrients in the soil can be absorbed and utilized by corn, so a soil nutrient correction coefficient must be multiplied. Research on formula fertilization parameters in various provinces of China shows that the correction coefficient for alkaline hydrolyzable nitrogen is between 0.3-0.7, the correction coefficient for available phosphorus is between 0.4-0.5, and the correction coefficient for available potassium is between 0.5-0.85.
The utilization rates of nitrogen, phosphorus and potassium chemical fertilizers are: nitrogen 30%-35%, phosphorus 10%-20%, potassium 40%-50%.
3. Determine the corn fertilizer application amount
With the nutrient amount required throughout the corn growth period, the soil nutrient supply, and the fertilizer utilization rate, the corn fertilizer application amount can be calculated directly. Then, by converting the pure nutrient amount into the actual amount of fertilizer, it can be used to guide fertilization. According to the data in 1 and 2, for a corn yield of 600 kg per mu, the required pure nitrogen amount is (15-18 × 0.6) ÷ 0.30 = 14 kg. The phosphorus amount is (7.2-6 × 0.5) ÷ 0.2 = 21 kg. Considering that phosphorus fertilizer has an obvious residual effect, the phosphorus fertilizer can be applied at half, that is, 10 kg. The potassium amount is (12-13.5 × 0.6) ÷ 0.50 = 8 kg. If diammonium phosphate, urea and potassium chloride are applied, then per mu 20 kg-22 kg of diammonium phosphate, 22 kg-25 kg of urea, and 14 kg of potassium should be applied.
4. Application of micronutrient fertilizers
Corn is very sensitive to zinc. If the available zinc in the soil is less than 0.5 mg/kg-1.0 mg/kg, zinc fertilizer needs to be applied. The availability of zinc in soil is higher under acidic conditions than under alkaline conditions, so alkaline and calcareous soils are now prone to zinc deficiency. In areas where phosphate fertilizer has been applied for a long time, due to the antagonistic effect between phosphorus and zinc, zinc deficiency is easily induced and should be supplemented. Commonly used zinc fertilizers include zinc sulfate and zinc chloride. The base fertilizer application rate per mu is 0.5 kg-2.5 kg, seed dressing is 4 g/kg-5 g/kg, and the seed soaking concentration is 0.02%-0.05%. If the compound fertilizer contains a certain amount of zinc, there is no need to apply zinc fertilizer separately.
Corn fertilization methods
1. Base fertilizer
2000 kg-3000 kg of organic fertilizer, all phosphate fertilizer, 1/3 nitrogen fertilizer, and all potassium fertilizer are used as base fertilizer or seed fertilizer. It can be applied once into the sowing furrow together with plowing and ridging, so that the fertilizer is applied into the 10 cm-15 cm plow layer. All chemical fertilizers can be used as base fertilizer.
2. Seed fertilizer
Seed fertilizer is the most economical and effective fertilization method. There are many ways to apply seed fertilizer, such as: seed dressing, seed soaking, band application, and hole application. For seed dressing, humic acid, biological fertilizer and micronutrient fertilizer can be selected; dissolve the fertilizer, spray it on the corn seeds, stir while spraying, so that the fertilizer solution evenly adheres to the seed surface, and sow after drying in the shade.
Seed soaking: dissolve the fertilizer to make a certain concentration, put the seeds into the solution and soak for 12 hours, then sow immediately after drying in the shade.
Band application and hole application: chemical fertilizers are suitable for band application and hole application, and the amount of chemical fertilizer used as seed fertilizer is 2 kg-5 kg. But the fertilizer must be separated from the seeds; deeper application is better, with a depth of 10 cm-15 cm being suitable. Urea, ammonium bicarbonate, ammonium chloride and potassium chloride are not suitable as seed fertilizer.
3. Topdressing
The remaining 2/3 of the nitrogen fertilizer is used as topdressing. Topdressing is divided into four topdressing periods: seedling fertilizer, stalk fertilizer, ear fertilizer and grain fertilizer, and the following two periods are taken as the key ones:
Stalk fertilizer: apply within 10 days after jointing, which promotes stem growth and young ear differentiation. Use 1/3 of the nitrogen fertilizer in the topdressing as jointing fertilizer, combined with hoeing and ridging, with a distance of 5 cm-7 cm between the fertilizer and the seedlings.
Ear fertilizer: apply the remaining nitrogen fertilizer 10 days--15 days before corn tasseling at the large trumpet stage, which can promote larger ears and more grains, and has a good effect on later grain filling.