When should spring corn be sown? How long can it sprout after sowing? When do you apply fertilizer? How to fertilize? (with sowing time in different places)

Every April, most parts of our country begin to sow corn, but due to local climatic factors, we still need to master certain techniques if we want to plant corn well. when will spring corn be sown? How long can it sprout after sowing? When do you apply fertilizer? How to fertilize?

Sowing time:

The sowing time of spring corn is from the end of April to the beginning of May. After sowing, only when the soil temperature of 10 cm stably passes through 12 ℃ can the effect of germination be achieved in 7 days. if the ground temperature does not reach this temperature, the corn seeds will stay in the soil for too long, which will affect the germination rate, and the barely germinated seeds will form weak seedlings. Therefore, we remind the broad masses of farmers that this year's spring sowing corn must timely grasp the sowing time according to the change of temperature.

Do not sow too early, spring corn is not sown earlier, the higher the yield. Planting too early, not only the yield is low, but also the occurrence of diseases and insect pests is quite serious. Such as rough dwarf disease, red spider and corn size spot disease and so on. This is because the corn planted at this time is in the season of high temperature and rain during pollination and grain filling, which is very easy to cause baldness or lack of grains. It is understood that the highest yield of corn can be achieved only when it is planted 15-20 days before the local wheat harvest.

In addition, it is necessary to choose a suitable variety. The selection of maize varieties should not only adapt to the local weather and climate, but also look at its lodging resistance, stress resistance and other comprehensive characteristic index, otherwise it is very easy to appear the phenomenon of serious baldness and shrunken grains.

Growth cycle:

The imbibition and embryo germination were found on the first day after the corn seeds were sown.

A week later, the buds broke through the soil, and the bright yellow buds gradually turned green in the sunlight.

After about 27 days, the seedlings gradually grew up and began to jointing.

At 52 days, the corn filaments began to be pulled out, and the male pollen appeared at the top; about 90-100 days after fertilization, the corn cobs grew bigger and bigger, and the corn filaments slowly withered or fell off and grew into corn cobs.

Fertilization time and skills:

In a certain range, the yield of maize increased with the increase of fertilizer application. Accurately determining the amount of fertilizer application is an important issue to achieve high, stable and high efficiency of maize. However, how to determine the amount of fertilizer application is a very complex problem.

During the growth and development of maize to form yield, the nutrients absorbed are not only the nutrients stored in the soil, but also the nutrients applied to the fertilizer in the current season. The amount and proportion of nutrients absorbed from soil storage or fertilizer are affected by many factors, so it is difficult to determine the amount of fertilizer accurately. There are many methods to determine the amount of fertilizer applied to corn in theory, but all of them are complicated.

Soil testing and fertilization can be carried out where there are conditions, and the content of various nutrients in the soil can be tested every 3-5 years, and then according to the fertilizer demand of maize, planned yield, soil fertilizer supply capacity, fertilizer utilization rate and other factors, the following formula is used to roughly calculate the amount of fertilizer application.

1. Characteristics of fertilizer requirement for corn

The main results are as follows: 1. Characteristics of nutrient demand of maize in different growth periods.

The proportion of nutrients required by maize is different in each growth period. From emergence to jointing, corn absorbs 2.5% of nitrogen, 1.12% of available phosphorus and 3% of available potassium; from jointing to flowering, 51.15% of nitrogen, 63.81% of available phosphorus and 97% of available potassium are absorbed; from flowering to maturity, 46.35% of nitrogen, 35.07% of available phosphorus and 0% of available potassium are absorbed.

Critical period of corn nutrition:

The critical period of phosphorus nutrition in maize is in the three-leaf stage, which is generally the period when seed nutrition changes to soil nutrition, while the critical period of nitrogen in maize is later than phosphorus, usually in the period when vegetative growth changes to reproductive growth. In the critical period, the demand for nutrients is not great, but the nutrients should be comprehensive and the proportion should be appropriate. During this period, too much or too little or unbalanced nutrients will have obvious adverse effects on the growth and development of corn, and no matter how to supplement the lack of nutrients in the future will not help.

Maximum efficiency period of corn nutrition:

The maximum efficiency of corn is in the stage of big trumpet mouth. This is the period of the fastest and largest nutrient absorption of corn. During this period, the absolute and relative amount of nutrients needed by corn are the largest, the absorption rate is the fastest, and the role of fertilizer is the biggest. At this time, the appropriate amount of fertilizer application, the yield-increasing effect of corn is the most obvious.

2. The demand for nutrients in the whole growth period of maize.

The growth of corn needs to absorb a variety of mineral nutrients from the soil, of which nitrogen is the most, potassium is the second, and phosphorus is the third.

Generally, for every 100 kg seeds, 2.5 kg of pure nitrogen, 1.2 kg of phosphorus pentoxide and 2.0 kg of potassium oxide need to be absorbed from the soil. The ratio of nitrogen, phosphorus and potassium is 1 ∶ 0.48 ∶ 0.8.

Fertilizer application rate = (planned output demand for a certain factor-soil supply to a certain factor) / (the content of an element in fertilizer (%) × fertilizer utilization rate (%)), the fertilizer utilization rate varies greatly. According to the experiment, the general organic farm fertilizer utilization rate is about 30%, the nitrogen fertilizer utilization rate is about 40%, the nitrogen fertilizer utilization rate is about 40%, and the phosphorus and potassium fertilizer is about 30%, 40%, 40%.

How much fertilizer do you need to apply to the planned 500 kg per mu corn grain? It is assumed that during 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 nutrient use efficiency of nitrogen, phosphorus pentoxide and potassium oxide in soil are 50%, 70% and 30%, respectively. When the national fertilizer experiment averages 500 kg per mu, 2.9 kg of nitrogen, 1.2 kg of phosphorus and 2.4 kg of potassium are needed for every 100 kg of grain, and the application amount of urea, calcium superphosphate and potassium chloride is calculated (urea contains 46% of available nitrogen, calcium superphosphate contains 16% of available phosphorus, potassium chloride contains 50% of available potassium).

2. Amount of fertilizer applied to corn

1. Determine the target output

The target yield is how much corn should be planted in the current year, and it is determined by the soil fertility of the cultivated land. In addition, according to the average yield of corn in the first three years of the plot, the target yield of corn can be increased by 10% and 15%. For example, a certain plot is a highly fertile soil, and the planned yield of corn in that year reached 600 kg. The nutrients of nitrogen, phosphorus and potassium needed for the whole growth period of corn were 15 kg, 7.2 kg and 12 kg respectively.

2. Calculate the soil nutrient supply.

Determine the number of available nutrients in the soil, and then calculate the number of nutrients in 1 mu of land. If the measured value of soil alkali hydrolyzable nitrogen, available phosphorus content and available potassium content are 120mg / kg, 40mg / kg and 90mg / kg, respectively, the total amount of available alkali hydrolyzable nitrogen in one mu of soil is 150000 kg × 120mg / kg × 10 to the negative 6th power = 18kg, the total amount of available phosphorus is 6kg and the total amount of available potassium is 13.5kg.

As many soil factors affect the availability of soil nutrients, all available nutrients in the soil can not be absorbed and utilized by corn, which needs to be multiplied by a soil nutrient correction coefficient. The study on the formula fertilization parameters of various provinces in China shows that the correction coefficients of alkali hydrolyzable nitrogen, available phosphorus and available potassium are 0.3-0.7, 0.4-0.5 and 0.5-0.85, respectively.

The utilization rates of nitrogen, phosphorus and potassium fertilizers are as follows: nitrogen 30% Mel 35%, P 10%-20%, K 40% Mel 50%.

3. Determine the amount of fertilizer applied to corn.

With the amount of nutrients, soil nutrient supply and fertilizer use efficiency needed for the whole growth period of corn, the amount of fertilizer application of corn can be calculated directly. Then the pure nutrient content is converted into the actual amount of fertilizer, which can be used to guide fertilization. According to the data in 1 and 2, the yield of corn per mu is 600 kg, and the amount of pure nitrogen required is (15-18 × 0.6) / 0.30 × 14 kg. The amount of phosphorus is (7.2-6 × 0.5) / 0.2-21 kg. Considering the obvious after-effect of phosphate fertilizer, the application of phosphate fertilizer can be halved, that is, 10 kg. The amount of potassium is (12-13.5 × 0.6) / 0.508 kg. If diammonium phosphate, urea and potassium chloride are applied, 20 kg-22 kg of diammonium phosphate, 22 kg-25 kg of urea and 14 kg of potassium should be applied per mu.

4. Application of micro-fertilizer

Corn is very sensitive to zinc, and zinc fertilizer is needed if the available zinc in the soil is less than 0.5-1.0 mg / kg. The availability of zinc in soil is higher in acidic conditions than in alkaline conditions, so alkaline and calcareous soils are prone to zinc deficiency. In the areas where phosphate fertilizer is applied for a long time, zinc deficiency is easy to be induced due to the antagonism between phosphorus and zinc, which should be supplemented. Commonly used zinc fertilizers are zinc sulfate and zinc chloride, the amount of base fertilizer per mu is 0.5-2.5 kg, seed dressing is 4-5 g / kg, and seed soaking concentration is 0.02% MUE 0.05%. If the compound fertilizer contains a certain amount of zinc, it is not necessary to apply zinc fertilizer alone.

III. Fertilization methods for corn

1. Base fertilizer

2000-3000 kg organic fertilizer, all phosphate fertilizer, 1 gram nitrogen fertilizer, all potash fertilizer as base fertilizer or seed fertilizer. Combined with ploughing and ridging, it can be applied to the sowing ditch at one time, so that the fertilizer can be applied to the plough layer of 10-15 cm. All chemical fertilizers can be used as base fertilizers.

2. Planting fertilizer

Growing fertilizer is the most economical and effective method of fertilization. There are many ways to apply seed fertilizer, such as seed dressing, seed soaking, strip application and hole application. In seed dressing, humic acid, biological fertilizer and micro-fertilizer can be selected to dissolve the fertilizer and spray it on the corn seed, so that the fertilizer solution can be evenly stained on the seed surface and sown after drying.

Soak the seeds: dissolve the fertilizer into a certain concentration, soak the seeds in the solution for 12 hours, and sow the seeds immediately after drying.

Strip application and hole application: chemical fertilizer is suitable for strip application and hole application, and the amount of chemical fertilizer used as seed fertilizer is 2-5 kg. But the fertilizer must be separated from the seeds; deep fertilization is better, with a depth of 10-15 cm. Urea, ammonium bicarbonate, ammonium chloride and potassium chloride are not suitable to be fertilizers.

3. Topdressing

The remaining 2x3 nitrogen fertilizer is used as topdressing. Topdressing is divided into four topdressing stages: seedling fertilizer, culm fertilizer, panicle fertilizer and grain fertilizer, with the following two periods as the focus:

Culm fertilizer: topdressing within 10 days after jointing can promote stem growth and young panicle differentiation. Make jointing fertilizer with 1amp 3 of nitrogen fertilizer in topdressing, combined with shovel, the distance between fertilizer and seedling is 5-7 cm.

Ear fertilizer: when the remaining nitrogen fertilizer was applied at the trumpet stage 10-15 days before heading, it could promote larger ear and more grains, and had a good effect on grain filling in the later stage.

Attach the best time for planting spring corn in different places:

Sowing time of spring corn in Shandong:

Because the sowing time of spring corn is early and the growth period is long, so the yield is high. Spring corn is generally planted in early April and harvested at the end of August in Shandong area.

Sowing time of spring corn in Northeast China:

The sowing time is after Grain Rain (about April 20) and before May 10, and the harvest is generally after October 1 and before October 20.

Sowing time of spring corn in South China:

Corn in the south can be planted for two seasons. In the case of the Yangtze River Basin, corn sown in spring is usually sown at the end of March and the beginning of April, and can be picked in the first and middle of July.

Sowing time of spring corn in Hebei:

Corn is divided into spring corn and autumn corn. Spring corn is sown in late April and early May and can be harvested in late August. Autumn corn can be sowed no later than mid-July and harvested in mid-late October at the latest.

Sowing time of spring corn in Anhui:

Usually, after the first rain in spring, it is the best time to grow spring corn. But now in order to prevent diseases and insect pests, it is recommended that spring corn should be sowed early, generally before the middle of April.

Sowing time of spring corn in Hunan:

Spring corn is generally sown in the first and middle of April and harvested in the first and middle of August. Summer corn was sown from late May to early June and matured in mid-late September.