Irrigation and fertilization method for high-efficiency production of cotton under zero chemical regulation condition

Abstract

The invention relates to an irrigation and fertilization method for high-efficiency production of cotton under a zero chemical regulation condition, which comprises the following steps: setting a plant water deficit index threshold value, and setting a water regulation coefficient according to the sensitive degree of cotton in each growth stage to water stress; optimally determining the total fertilization amount in the whole growth period of the cotton, and determining a nutrient regulation coefficient according to the sensitive degree of the cotton in each growth period to nutrient stress; continuously obtaining root zone soil moisture and salinity dynamic data, and evaluating a plant moisture deficit index; when the estimated value of the plant water deficit index threshold value is larger than the set threshold value, a valve is opened for irrigation, the irrigation quota is calculated, and staged pulse fertilizer injection or continuous variable fertilizer injection is adopted in the water and fertilizer integrated implementation process. According to the method, the water, fertilizer and salt environmental conditions of the soil are regulated in time through irrigation and fertilization, the growth process of the cotton is further regulated, especially the relation between vegetative growth and reproductive growth is optimized, excessive growth of the cotton is effectively prevented on the premise that growth regulators such as mepiquat chloride are not applied, and the aims of saving water and fertilizer, inhibiting salt, increasing yield and income and the like are achieved.

Description

Technical Field

[0001] The invention relates to an irrigation and fertilization method, in particular to an irrigation and fertilization method for efficient cotton production under zero chemical regulation conditions. Background Art

[0002] Cotton is originally a perennial plant. When the soil and climate and other environmental conditions are suitable, the early vegetative growth is too vigorous and the later reproductive growth is limited. The main manifestations are vigorous growth of branches and leaves, severe bud and boll shedding, delayed flowering and boll setting, prolonged growth period, and reduced yield and fiber quality. It can be seen that accurately regulating the growth process of cotton and coordinating the relationship between vegetative growth and reproductive growth are the key links to ensure efficient cotton production. For a long time, chemical control methods (referred to as chemical control) represented by spraying chlorpyrifos have been widely used due to their quick effect and simple operation (CN103039152A; CN14402841B). However, the implementation of chemical control will not only greatly increase the cost of cotton production, but also bring environmental pollution risks. In addition, due to the combined influence of many factors such as the types of growth regulators, cotton varieties and growth stages and planting patterns, irrigation and fertilization systems, soil and climate, it is still difficult to form a scientific, reasonable and accurate chemical control technology system or specification. The strong subjective experience has greatly affected its stability, resulting in reduced production and even total crop failure.

[0003] From the external environmental conditions and internal physiological mechanisms of cotton leggy growth, it can be seen that in addition to using chemical regulators to directly intervene in its growth and development process, timely adjusting the soil water, fertilizer and salt environmental conditions through irrigation and fertilization at each growth stage, actively applying different degrees of stress to regulate its growth and development process (referred to as water, fertilizer and salt regulation) is an effective way to prevent leggy growth. Obviously, the key link in the regulation of water, fertilizer and salt for cotton growth is irrigation and fertilization. In recent years, with the continuous development of intelligent irrigation and fertilization technology and systems, the accuracy of water, fertilizer and salt regulation in cotton fields has been greatly improved (CN103477948B; CN112369176A), but it still needs to be combined with chemical control. Therefore, it is necessary to further optimize the irrigation and fertilization method in order to fully utilize its positive effects while reducing the adverse effects of water, fertilizer and salt stress, reduce the redundancy of vegetative organ growth, promote the transfer of assimilated products to reproductive organs, and reduce the consumption of water and fertilizer resources, so as to achieve high yield and high efficiency. Summary of the invention

[0004] The purpose of the present invention is to propose an irrigation and fertilization method for efficient cotton production under zero chemical control conditions, that is, without spraying growth regulators, the cotton growth process is regulated by optimizing the irrigation and fertilization system so as to achieve the goals of saving water, saving fertilizer, inhibiting salt, increasing production and increasing income.

[0005] An irrigation and fertilization method for efficient cotton production under zero chemical regulation conditions comprises the following steps: Set the threshold of plant water deficit index and set the water regulation coefficient according to the sensitivity of cotton to water stress at each growth stage; Optimize the total amount of fertilizer applied during the entire growth period of cotton, and determine the nutrient regulation coefficient based on the sensitivity of cotton to nutrient stress at each growth stage; Continuously obtain dynamic data of soil moisture and salt in the root zone to evaluate plant water deficit index; When the estimated value of the plant water deficit index is greater than the set threshold, the valve is opened to irrigate, and the irrigation quota is calculated according to the soil moisture profile in the root zone before irrigation and the moisture regulation coefficient; The initial value of the fertilization quota during each irrigation process is determined according to the total amount of fertilizer applied during the entire growth period and the aboveground dry matter accumulation curve, and then multiplied by the nutrient adjustment coefficient for correction to obtain the fertilization quota; Determine the irrigation amount and fertilizer amount in a single irrigation process according to the irrigation quota, fertilizer quota and irrigation area; The irrigation process is evenly divided from the beginning to the end based on the irrigation amount. n part( n ≥1), the cotton root zone from the maximum rooting depth to the ground surface is also divided into n The percentage of the area of ​​the closed figure of relative root length density corresponding to each section from the maximum rooting depth to the ground surface in the total area of ​​the root zone is calculated, and this is used as the percentage of fertilization in each time period from the beginning to the end of the irrigation process. That is, the fertilization ratio corresponding to the first stage of irrigation is the lowest part of the root zone. n The percentage of segment relative to root length density; The irrigation process uses water-fertilizer integration technology to apply fertilizer simultaneously. The amount of fertilizer applied at each irrigation stage is the product of the total amount of fertilizer applied during a single irrigation process and the fertilizer application ratio at that stage. When the actual irrigation volume reaches the calculated value, stop irrigation, re-estimate the plant water deficit index and prepare for the next irrigation and fertilization.

[0006] Furthermore, the cotton growth stages include seedling stage, bud stage, early flowering and boll stage, late flowering and boll stage, and boll opening stage; During the seedling stage, bud stage, late flowering and boll stage and boll opening stage, the water regulation coefficient is set to be less than 1.0; In the early stage of flowering and boll formation, the water regulation coefficient is set to be equal to or greater than 1.0, and the water regulation coefficient is increased as the soil salt content increases.

[0007] Furthermore, during the seedling stage, bud stage, late flowering and boll stage, and boll opening stage, the nutrient regulation coefficient is set to be less than 1.0, and the nutrient regulation coefficient during the late flowering and boll stage is determined based on the dry matter accumulation curve of the aboveground part of cotton while keeping the total amount of fertilizer applied during the entire growth period unchanged.

[0008] Furthermore, the threshold value of the plant water deficit index is evaluated according to ; Evaluation, where is the water-salt stress recovery coefficient taking into account the hysteresis effect of stress; It is a cross-adaptation factor to water-salt stress; and are soil water matrix potential and osmotic potential (cm), respectively; and are soil moisture and salt stress correction factors, respectively; z r is the relative depth of the soil layer, , z is the soil layer depth (cm), L r is the crop rooting depth (cm); is the relative root length density distribution, obtained by formula (2): ; In the formula p is the root system parameter. For cotton, p =1.96.

[0009] Furthermore, the irrigation quota is based on ; Calculation, where I is the irrigation quota (m 3 / mu); β is the soil irrigation wetness ratio; R is the salt elution coefficient; D w is the planned wet layer depth (cm), which is generally taken as 60 cm; C w To determine the moisture regulation coefficient of cotton at each growth stage; i f is the field water capacity (cm 3 cm -3 ); i ( z ) is the soil moisture content at each depth before irrigation (cm 3 cm -3 ); or is the effective utilization coefficient of field water.

[0010] Furthermore, the percentage of the area of ​​the closed figure of relative root length density corresponding to each section from the maximum rooting depth to the ground surface in the total area of ​​the entire root zone is specifically calculated according to the relative root length density distribution diagram shown in formula (2).

[0011] Beneficial effects of the present invention: Through irrigation and fertilization, the soil water, fertilizer and salt environment conditions are timely regulated and the cotton growth process is further regulated, especially the relationship between vegetative growth and reproductive growth is optimized, and the cotton leggy growth is effectively prevented without the application of growth regulators such as chlortetracycline, so as to achieve the goals of water saving, fertilizer saving, salt suppression, increased production and increased income. In the non-sensitive period (seedling stage, bud stage, late flowering and boll stage, boll opening stage), cotton suffers from a certain degree of water, fertilizer and salt stress, and even after irrigation and fertilization, the phenomenon of "large water and large fertilizer" will not occur, thereby inhibiting the level of gibberellins in the plant (further inhibiting the cell elongation and division rate), preventing the excessive vegetative growth of cotton, greed for green and late maturity; in the key growth period (late flowering and boll stage) when cotton is very sensitive to water, fertilizer and salt stress, the water and nutrient supply is sufficient, the salt stress is greatly reduced, the leaf aging rate is effectively reduced, the leaf area index and net photosynthetic rate are maintained at a higher level for a longer period of time, the accumulation of photosynthetic products is increased, the boll and fiber development is promoted, and the cotton yield and fiber quality are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention has the following accompanying drawings: Figure 1 The present invention shows the influence on cotton growth and yield compared with the traditional irrigation and fertilization method. DETAILED DESCRIPTION

[0013] In order to make the objects, advantages and features of the present invention more obvious, a detailed description is given below in conjunction with the accompanying drawings and specific embodiments.

[0014] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, but should not be construed as limiting the present invention.

[0015] The technical solutions and steps adopted by the present invention are as follows: 1) Before sowing, set the threshold of plant water deficit index (PWDI) according to the expected production target (yield and water and fertilizer use efficiency, etc.), and set the water regulation coefficient according to the sensitivity of cotton to water stress in each major growth stage (seedling stage, bud stage, early boll formation, late boll formation, boll opening stage). Generally, cotton is not very sensitive to water stress in the seedling stage, bud stage, late boll formation and boll opening stage, and the water regulation coefficient can be set to less than 1.0. However, cotton is very sensitive to water stress in the key growth stage (early boll formation), and the water regulation coefficient can be set to be equal to or even greater than 1.0. In addition, as the soil salt content increases, the water regulation coefficient should be appropriately increased; 2) Before sowing, optimize and determine the total amount of fertilizer to be applied during the entire growth period of cotton, and then determine the nutrient adjustment coefficient for the periods with lower nutrient demand and less sensitivity to nutrient stress (seedling stage, bud stage, late flowering and boll stage, boll opening stage), which is generally set to be less than 1.0. Finally, determine the nutrient adjustment coefficient for the key growth period (early flowering and boll stage) based on the dry matter accumulation curve of the aboveground part of cotton while keeping the total amount of fertilizer applied during the entire growth period unchanged; 3) During the cotton growth period, the dynamic data of soil moisture and salt in the root zone were continuously obtained and the PWDI was evaluated according to formula (1): ; In the formula is the water-salt stress recovery coefficient taking into account the hysteresis effect of stress; Cross-adaptation factors to water-salt stress; h and f are soil water matrix potential and osmotic potential (cm), respectively; and are soil moisture and salt stress correction factors, respectively; z r is the relative depth of the soil layer, , z is the soil layer depth (cm), L r is the crop rooting depth (cm); is the relative root length density distribution, obtained by formula (2): ; In the formula p is the root system parameter. For cotton, p =1.96; 4) When the estimated value of PWDI is greater than the set threshold, the valve is opened to fill water, and the water filling quota is calculated according to formula (3): ; In the formula I is the irrigation quota (m 3 / mu); β is the soil irrigation wetness ratio; R is the salt elution coefficient; D w is the planned wet layer depth (cm), which is generally taken as 60 cm; C w is the moisture regulation coefficient of cotton at each growth stage determined in step 1); i f is the field water capacity (cm 3 cm -3 ); i ( z ) is the soil moisture content at each depth before irrigation (cm 3 cm -3 ); or is the effective utilization coefficient of field water; 5) Determine the initial value of fertilizer quota for each irrigation process according to the total amount of fertilizer applied during the whole growth period and the aboveground dry matter accumulation curve, and then multiply it by the nutrient adjustment coefficient of each growth stage of cotton determined in step 2) ( C f ) is corrected to obtain the fertilizer quota (F 0 , kg / mu); 6) Determine the amount of water and fertilizer to be applied during a single irrigation process based on the irrigation quota, fertilizer quota and irrigation area; 7) Based on the irrigation volume, the irrigation process is evenly divided from the beginning to the end n Accordingly, the cotton root zone is divided into n Then, according to the relative root length density distribution diagram shown in formula (2), the area and percentage of the closed figure corresponding to each section from the maximum rooting depth to the surface are calculated respectively, and it is used as the percentage of fertilization in each time period from the beginning to the end of the irrigation process. That is, the fertilization ratio corresponding to the first irrigation stage is the lowest part of the root zone. n The percentage of segment relative to root length density, and so on; 8) During the irrigation process, water-fertilizer integration technology is used to apply fertilizer simultaneously. The amount of fertilizer applied at each irrigation stage is the product of the total amount of fertilizer applied during a single irrigation process and the fertilizer application ratio at that stage; 9) When the actual irrigation volume reaches the calculated value, stop irrigation, recalculate PWDI and prepare for the next irrigation and fertilization. Do not spray growth regulators such as DCP during the whole process. From 2021 to 2023, with the local traditional irrigation and fertilization method as the control, the sub-film drip irrigation cotton test verification and demonstration application were carried out in Shawan City, Xinjiang Uygur Autonomous Region for the technology of the present invention. The soil in the cotton field from 0 to 80 cm was loam, and the average soil salt content was 4.19 g / kg. The "dry sowing and wet out" planting technology was adopted, and the planting pattern was "one film, three tubes and six rows". The film spacing was 40 cm, the film width was 190 cm, and the row spacing was arranged in a wide and narrow row manner of "10-66-10-66-10 cm". The plant spacing was 12 cm, and no irrigation and fertilization was performed during the boll opening period. For the local traditional irrigation and fertilization method, irrigation was performed 8 to 11 times during the whole growth period, and the irrigation quota was 250 to 300 m 3 / mu, the application amount of N, P2O5, and K2O during the whole growth period is 17.8, 9.3, and 8.7 kg / mu respectively. The fertilizer quota during each irrigation process is determined according to the dry matter accumulation curve of the aboveground part of cotton. During the implementation of the water-fertilizer integration technology, fertilizer is injected within 25 to 30 minutes before stopping irrigation. Dicalcium is sprayed within 1-2 days before each irrigation in the bud stage, early flowering and boll stage, and late flowering and boll stage. For the technology of the present invention, the PWDI irrigation threshold of cotton during the whole growth period is taken as 0.5. When determining the irrigation quota, two sets of water regulation coefficients (0.8, 0.9, 1.0, 0.9; 0.6, 0.7, 1.0, 0.7) are set for the seedling stage, bud stage, early flowering and boll stage, and late flowering and boll stage. The N, P2O5, and K2O during the whole growth period of cotton are determined by the aboveground dry matter accumulation curve. During the implementation of the water-fertilizer integration technology, fertilizer is injected within 25 to 30 minutes before stopping irrigation. Dicalcium is sprayed within 1-2 days before each irrigation in the bud stage, early flowering and boll stage, and late flowering and boll stage. The application rates were 80% of the local traditional irrigation fertilization methods. When determining the fertilizer quota during a certain irrigation process in the seedling stage, bud stage, early flowering and boll stage, and late flowering and boll stage, four sets of nutrient adjustment coefficients were set (0.8, 0.9, 1.1, 0.9; 0.7, 0.8, 1.3, 0.8; 0.6, 0.7, 1.5, 0.7; 0.5, 0.6, 1.7, 0.6). During the implementation of water-fertilizer integration technology, the injection ratios of fertilizers before, during and after irrigation were 11%, 32% and 57% respectively, and there was no need to spray chlorpyrifos during the entire growth period.

[0016] The results of the test and demonstration application show that: 1) Compared with the traditional irrigation and fertilization method of spraying 6 to 8 times of DCP during the whole growth period, the application of the technology of the present invention can effectively prevent the excessive growth of cotton, although no chemical regulation is implemented, and can achieve the goals of saving water, saving fertilizer, inhibiting salt, increasing production and increasing income while maintaining the quality of cotton fiber. It proves that it is feasible to promote efficient production of cotton by using the technology of the present invention under zero chemical control conditions; 2) After screening, the optimal irrigation and fertilization technology mode of local sub-film drip irrigation under zero chemical control conditions is: the water regulation coefficients in the seedling stage, bud stage, early flowering and boll stage, and late flowering and boll stage are 0.8, 0.9, 1.0, and 0.9, respectively, and the nutrient regulation coefficients are 0.6, 0.7, 1.5, and 0.7, respectively; compared with the traditional irrigation and fertilization method, the application of this technology mode can save water by 10-17%, increase production by 5-12%, and increase income by 10-28% while saving 20% ​​of fertilizer (such as Figure 1 as shown).

Claims

1. A method for fertilizing and irrigating cotton for efficient production under zero chemical regulation conditions, characterized in that: The steps include: Set the threshold of plant water deficit index and set the water regulation coefficient according to the sensitivity of cotton to water stress at each growth stage; Optimize the total amount of fertilizer to be applied during the entire growth period of cotton, and determine the nutrient regulation coefficient according to the sensitivity of cotton to nutrient stress at each growth stage; Continuously obtain dynamic data of soil moisture and salt in the root zone to evaluate plant water deficit index; When the estimated value of the plant water deficit index is greater than the set threshold, the valve is opened to irrigate, and the irrigation quota is calculated according to the soil moisture profile in the root zone before irrigation and the moisture regulation coefficient; The initial value of the fertilization quota during each irrigation process is determined according to the total amount of fertilizer applied during the entire growth period and the aboveground dry matter accumulation curve, and then multiplied by the nutrient adjustment coefficient for correction to obtain the fertilization quota; Determine the irrigation amount and fertilizer amount in a single irrigation process according to the irrigation quota, fertilizer quota and irrigation area; The irrigation process is evenly divided from the beginning to the end based on the irrigation amount. n part( n ≥1), the cotton root zone from the maximum rooting depth to the ground surface is also divided into n The percentage of the area of ​​the closed figure of relative root length density corresponding to each section from the maximum rooting depth to the ground surface in the total area of ​​the root zone is calculated, and this is used as the percentage of fertilization in each time period from the beginning to the end of the irrigation process. That is, the fertilization ratio corresponding to the first stage of irrigation is the lowest part of the root zone. n The percentage of segment relative to root length density; The irrigation process uses water-fertilizer integration technology to apply fertilizer simultaneously. The amount of fertilizer applied at each irrigation stage is the product of the total amount of fertilizer applied during a single irrigation process and the fertilizer application ratio at that stage. When the actual irrigation volume reaches the calculated value, stop irrigation, re-estimate the plant water deficit index and prepare for the next irrigation and fertilization.

2. The method for fertilizing and irrigating cotton for efficient production under zero chemical regulation conditions as claimed in claim 1, characterized in that: The cotton growth stages include seedling stage, bud stage, early flowering and boll stage, late flowering and boll stage, and boll opening stage; During the seedling stage, bud stage, late flowering and boll stage and boll opening stage, the water regulation coefficient is set to be less than 1.0; In the early stage of flowering and boll formation, the water regulation coefficient is set to be equal to or greater than 1.0, and the water regulation coefficient is increased as the soil salt content increases.

3. The method for fertilizing and irrigating cotton for efficient production under zero chemical regulation conditions as claimed in claim 1, characterized in that: During the seedling stage, bud stage, late flowering and boll stage, and boll opening stage, the nutrient adjustment coefficient is set to be less than 1.

0. The nutrient regulation coefficient at the later stage of flowering and boll formation is determined according to the dry matter accumulation curve of the aboveground part of cotton while keeping the total amount of fertilizer applied during the whole growth period unchanged.

4. The method for fertilizing and irrigating cotton for efficient production under zero chemical regulation conditions as claimed in claim 1, characterized in that: The threshold value of plant water deficit index is evaluated according to ； Evaluation, where is the water-salt stress recovery coefficient taking into account the hysteresis effect of stress; It is a cross-adaptation factor to water-salt stress; and are soil water matrix potential and osmotic potential (cm), respectively; and are soil moisture and salt stress correction factors, respectively; is the relative depth of the soil layer, , z is the soil layer depth (cm), is the crop rooting depth (cm); is the relative root length density distribution, obtained by formula (2): ； In the formula p is the root system parameter. For cotton, p =1.

96.

5. The method for fertilizing and irrigating cotton for efficient production under zero chemical regulation conditions as claimed in claim 1, characterized in that: The irrigation quota is based on ； Calculation, where I is the irrigation quota (m 3 / mu); β is the soil irrigation wetness ratio; R is the salt elution coefficient; D w is the planned wet layer depth (cm), which is generally taken as 60 cm; C w To determine the moisture regulation coefficient of cotton at each growth stage; θ f is the field water capacity (cm 3 cm -3 ); is the soil moisture content at each depth before irrigation (cm 3 cm -3 ); η is the effective utilization coefficient of field water.

6. The method for fertilizing and irrigating cotton for efficient production under zero chemical regulation conditions as claimed in claim 1, characterized in that: The percentage of the area of ​​the closed figure of relative root length density corresponding to each section from the maximum rooting depth to the ground surface in the total area of ​​the entire root zone is specifically calculated according to the relative root length density distribution diagram shown in formula (2).

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