An irrigation and fertilization method for efficient production of cotton under zero-chemical regulation conditions

Abstract

The present application relates to a kind of irrigation fertilization methods for efficient production of cotton under zero chemical regulation conditions, comprising setting plant water deficit index threshold, setting water regulation coefficient according to the sensitivity of cotton to water stress at each growth stage;Optimizing the total amount of fertilization during the whole growth period of cotton, determine the nutrient regulation coefficient according to the sensitivity of cotton to nutrient stress at each growth stage;Continuous acquisition of root zone soil water and salt dynamic data, evaluate plant water deficit index;When the estimated value of plant water deficit index threshold is greater than the set threshold, open the valve and irrigate, calculate irrigation quota, and use phased pulse injection fertilization or continuous variable injection fertilization during the implementation process of water and fertilizer integration.The present application regulates soil water and fertilizer salt environment conditions and further regulates cotton growth process through irrigation fertilization, especially optimizes the relationship between vegetative growth and reproductive growth, effectively prevents cotton from overgrowth under the premise of free application of growth regulators such as mepiquat chloride, and achieves the goals of water saving, fertilizer saving, salt inhibition, yield increase and income increase.

Description

Technical Field

[0001] This invention relates to an irrigation and fertilization method, and more particularly to an irrigation and fertilization method for efficient cotton production under zero chemical control conditions. Background Technology

[0002] Cotton is a perennial plant. Under suitable soil and climate conditions, it exhibits excessive vegetative growth in the early stages while reproductive growth is restricted in the later stages. This manifests as vigorous vegetative growth, severe boll shedding, delayed flowering and boll formation, prolonged growing season, and reduced yield and fiber quality. Therefore, precise regulation of the cotton growth process and coordination between vegetative and reproductive growth are crucial for ensuring efficient cotton production. For a long time, chemical regulation methods (referred to as chemical control), typically represented by the application of mepiquat chloride, have been widely used due to their rapid effectiveness and ease of operation (CN103039152A; CN14402841B). However, implementing chemical control not only significantly increases cotton production costs but also poses environmental pollution risks. Furthermore, due to the combined influence of numerous factors such as the type of growth regulator, cotton variety and growth stage, planting method, irrigation and fertilization system, soil, and climate, it is still difficult to establish a scientifically sound and precise chemical control technology system or standard. The strong reliance on subjective experience greatly affects its stability, leading to frequent yield reductions and even crop failures.

[0003] Based on the external environmental conditions and internal physiological mechanisms of excessive vegetative growth in cotton, it is evident that, in addition to directly intervening in its growth and development process with chemical regulators, timely adjustment of soil water, fertilizer, and salt conditions through irrigation and fertilization at each growth stage, and proactive application of varying degrees of stress to regulate its growth and development (referred to as water, fertilizer, and salt regulation), is an effective method to prevent excessive vegetative growth. Clearly, the key link in water, fertilizer, and salt regulation for cotton growth is irrigation and fertilization. In recent years, with the continuous development of intelligent irrigation and fertilization technologies and systems, the precision of water, fertilizer, and salt regulation in cotton fields has been significantly improved (CN103477948B; CN112369176A), but it still needs to be combined with chemical control. Therefore, it is necessary to further optimize irrigation and fertilization methods to fully utilize their positive effects while reducing the adverse effects of water, fertilizer, and salt stress, thereby reducing redundant growth of vegetative organs, promoting the transfer of assimilated products to reproductive organs, and reducing water and fertilizer resource consumption, thus achieving high yield and high efficiency. Summary of the Invention

[0004] The purpose of this 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 in order to achieve the goals of water conservation, fertilizer saving, salt suppression, increased yield and income.

[0005] An irrigation and fertilization method for efficient cotton production under zero chemical regulation conditions includes the following steps:

[0006] Set a threshold for the plant water deficit index and set a water regulation coefficient based on the sensitivity of cotton to water stress at each growth stage.

[0007] The total amount of fertilizer applied throughout the entire growth period of cotton was optimized and determined, and the nutrient regulation coefficient was determined based on the sensitivity of cotton to nutrient stress at each growth stage.

[0008] Continuously acquire dynamic data on soil moisture and salinity in the root zone to assess the plant water deficit index;

[0009] When the estimated value of the plant water deficit index is greater than the set threshold, the valve is opened for irrigation. The irrigation quota is calculated based on the soil moisture content profile of the root zone before irrigation and the water regulation coefficient.

[0010] The initial value of the fertilization quota for each irrigation process is determined by the total amount of fertilizer applied during the entire growth period and the aboveground dry matter accumulation curve, and then corrected by multiplying it by the nutrient adjustment coefficient to obtain the fertilization quota.

[0011] The amount of water and fertilizer applied during a single irrigation process is determined based on the irrigation quota, fertilizer quota, and irrigation area.

[0012] Based on the amount of irrigation water, the irrigation process is divided evenly from beginning to end. n part( n ≥1), the cotton root zone is also divided from the maximum rooting depth to the ground surface. n The percentage of the area of ​​the closed loop of relative root length density corresponding to each segment from the maximum root depth to the ground surface is calculated as the percentage of the total area of ​​the root zone. This percentage is then used as the percentage of fertilization applied during each time period from the beginning to the end of the irrigation process. Specifically, the fertilization ratio corresponding to the first stage of irrigation is the percentage of the lowest root zone. n The percentage of the relative root length density of the segment;

[0013] The irrigation process adopts the integrated water and fertilizer technology for simultaneous fertilization. The amount of fertilizer applied in each irrigation stage is the product of the total amount of fertilizer applied in a single irrigation process and the proportion of fertilizer applied in that stage.

[0014] 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.

[0015] Furthermore, the cotton growth stages include the seedling stage, budding stage, pre-flowering and boll-forming stage, post-flowering and boll-forming stage, and boll-opening stage;

[0016] During the seedling stage, bud stage, late flowering and boll-forming stage, and boll-opening stage, the moisture regulation coefficient should be less than 1.0;

[0017] 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 salinity increases.

[0018] Furthermore, during the seedling stage, budding stage, late flowering and boll-forming stage, and boll-opening stage, the nutrient regulation coefficient is set to be less than 1.0. While keeping the total amount of fertilizer applied throughout the entire growth period constant, the nutrient regulation coefficient during the late flowering and boll-forming stage is determined based on the aboveground dry matter accumulation curve of cotton.

[0019] Furthermore, the threshold for assessing the plant water deficit index is based on...

[0020] ;

[0021] Evaluation, in the formula The water-salt stress recovery coefficient takes into account the stress hysteresis effect; It is a cross-adaptation factor for water and salt stress; and These are soil water matrix potential and osmotic potential (cm), respectively. and These are soil moisture and salt stress correction factors, respectively; z r This represents the relative depth of the soil layer. z represents the soil depth (cm). L r The depth of crop roots (cm); The relative root length density distribution is obtained from equation (2):

[0022] ;

[0023] In the formula p For cotton, as a root system morphology, p =1.96.

[0024] Furthermore, the irrigation quota is based on

[0025] ;

[0026] Calculate, where I For irrigation quota (m 3 / mu); β For soil irrigation moisture ratio; R This is the salt leaching coefficient; D w The planned wetting layer depth (cm) is generally taken as 60 cm; C w The water regulation coefficients for each stage of cotton growth are determined. i f Field holding capacity (cm²) 3 cm -3 ); i ( z) represents the soil moisture content (cm³) at various depths before irrigation. 3 cm -3 ); or This is the field water use efficiency coefficient.

[0027] Furthermore, the percentage of the area of ​​the closed relative root length density diagram corresponding to each segment from the maximum root depth to the ground surface in the total area of ​​the root zone is specifically calculated according to the relative root length density distribution diagram shown in equation (2).

[0028] The beneficial effects of this invention are:

[0029] By timely regulating soil water, fertilizer, and salt conditions through irrigation and fertilization, and further controlling the cotton growth process, especially optimizing the relationship between vegetative and reproductive growth, excessive vegetative growth can be effectively prevented without the need for growth regulators such as mepiquat chloride, achieving goals such as water conservation, fertilizer saving, salt suppression, increased yield, and increased income. During non-sensitive periods (seedling stage, bud stage, late boll-forming stage, and boll-opening stage), cotton experiences a certain degree of water, fertilizer, and salt stress. Even after irrigation and fertilization, the phenomenon of "excessive water and fertilizer" will not occur, thus inhibiting gibberellin levels in the plant (further inhibiting cell elongation and division rates), preventing excessive vegetative growth, delayed maturity, and excessive vegetative growth. During the critical growth period when cotton is highly sensitive to water, fertilizer, and salt stress (late boll-forming stage), sufficient water and nutrient supply significantly reduces salt stress, effectively slowing leaf senescence, maintaining a higher leaf area index and net photosynthetic rate for a longer period, increasing the accumulation of photosynthetic products, promoting boll and fiber development, and improving cotton yield and fiber quality. Attached Figure Description

[0030] The present invention includes the following figures:

[0031] Figure 1 This invention relates to the impact of traditional irrigation and fertilization methods on cotton growth and yield. Detailed Implementation

[0032] To make the objectives, advantages and features of the present invention more apparent, a detailed description is provided below in conjunction with the accompanying drawings and specific embodiments.

[0033] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0034] The technical solution and steps adopted in this invention are as follows:

[0035] 1) Before sowing, set the Plant Water Deficiency Index (PWDI) threshold according to the expected production targets (yield and water and fertilizer use efficiency, etc.), and set the water regulation coefficient according to the sensitivity of cotton to water stress at each major growth stage (seedling stage, bud stage, early flowering and boll formation stage, late flowering and boll formation stage, and boll opening stage). Generally, cotton is not very sensitive to water stress during the seedling stage, bud stage, late flowering and boll formation stage, and boll opening stage, so the value can be set to less than 1.0. However, cotton is very sensitive to water stress during the critical growth stage (early flowering and boll formation stage), so the value can be set to equal to or even greater than 1.0. Furthermore, as the soil salinity increases, the water regulation coefficient should be appropriately increased.

[0036] 2) Before sowing, optimize and determine the total amount of fertilizer applied during the entire growth period of cotton. Then, determine the nutrient regulation coefficient for the periods with lower nutrient requirements and less sensitivity to nutrient stress (seedling stage, bud stage, late flowering and boll opening stage), generally setting it to be less than 1.0. Finally, while keeping the total amount of fertilizer applied during the entire growth period unchanged, determine the nutrient regulation coefficient for the key growth period (early flowering and boll opening stage) based on the aboveground dry matter accumulation curve of cotton.

[0037] 3) During the cotton growing season, continuously acquire dynamic data on soil moisture and salinity in the root zone and assess PWDI according to formula (1):

[0038] ;

[0039] In the formula The water-salt stress recovery coefficient takes into account the stress hysteresis effect; Water and salt stress cross-adaptation factor; h and f These are soil water matrix potential and osmotic potential (cm), respectively. and These are soil moisture and salt stress correction factors, respectively; z r This represents the relative depth of the soil layer. z represents the soil depth (cm). L r The depth of crop roots (cm); The relative root length density distribution is obtained from equation (2):

[0040] ;

[0041] In the formula p For cotton, as a root system morphology, p =1.96;

[0042] 4) When the estimated PWDI value is greater than the set threshold, open the valve to inject water, and calculate the water injection quota according to formula (3):

[0043] ;

[0044] In the formula I For irrigation quota (m 3 / mu); β For soil irrigation moisture ratio; R This is the salt leaching coefficient; D w The planned wetting layer depth (cm) is generally taken as 60 cm; C w The water regulation coefficients for each growth stage of cotton determined in step 1); i f Field holding capacity (cm²) 3 cm -3 ); i ( z ) represents the soil moisture content (cm³) at various depths before irrigation. 3 cm -3 ); or The effective water use coefficient in the field;

[0045] 5) Determine the initial value of the fertilizer quota for each irrigation process based on the total fertilizer application during the entire growth period and the aboveground dry matter accumulation curve, and then multiply it by the nutrient regulation coefficient for each growth stage of cotton determined in step 2). C f The fertilization quota was revised accordingly to obtain the fertilization quota. F 0 (kg / mu);

[0046] 6) Determine the amount of water and fertilizer applied during a single irrigation process based on the irrigation quota, fertilizer quota, and irrigation area.

[0047] 7) Divide the irrigation process evenly from beginning to end based on the amount of irrigation water. n Accordingly, the cotton root zone is also divided into sections from the maximum rooting depth to the ground surface. n Then, according to the relative root length density distribution map shown in equation (2), calculate the area of ​​the closed figure corresponding to each segment from the maximum root depth to the ground surface and its percentage, and use it 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 root zone. n The percentage of the relative root length density of the segment, and so on;

[0048] 8) During the irrigation process, fertigation is carried out simultaneously using integrated water and fertilizer technology. The amount of fertilizer applied in each irrigation stage is the product of the total amount of fertilizer applied in a single irrigation process and the proportion of fertilizer applied in that stage.

[0049] 9) When the actual irrigation volume reaches the calculated value, stop irrigation, re-estimate the PWDI and prepare for the next irrigation and fertilization. Do not spray growth regulators such as mepiquat chloride throughout the process.

[0050] From 2021 to 2023, using local traditional irrigation and fertilization methods as a control, a trial verification and demonstration application of the technology of this invention was carried out in Shawan City, Xinjiang Uygur Autonomous Region, for drip irrigation cotton under plastic film. The soil in the cotton field from 0 to 80 cm was loam with an average soil salinity of 4.19 g / kg. The "dry sowing and wet emergence" planting technique was adopted, with a planting pattern of "one film, three pipes, and six rows". The film spacing was 40 cm, the film width was 190 cm, the row spacing was arranged in a wide-narrow row pattern of "10-66-10-66-10 cm", and the plant spacing was 12 cm. No irrigation or fertilization was performed during the boll opening stage. For the local traditional irrigation and fertilization methods, irrigation was carried out 8 to 11 times during the entire growth period, with an irrigation quota of 250 to 300 m³. 3 The application rates of N, P2O5, and K2O throughout the entire growth period are 17.8, 9.3, and 8.7 kg / mu, respectively. The fertilization quota for each irrigation period is determined based on the cotton aboveground dry matter accumulation curve. During the implementation of the fertigation technology, fertilizer is injected 25-30 minutes before irrigation stops. Mepiquat chloride is sprayed 1-2 days before each irrigation during the budding stage, early flowering and boll formation stage, and late flowering and boll formation stage. For this invention, the PWDI irrigation threshold for the entire cotton growth period is set to 0.5. When determining the irrigation quota, two sets of water adjustment coefficients are set for the seedling stage, budding stage, early flowering and boll formation stage, and late flowering and boll formation stage (0.8, 0.9, 1.0, 0.9; 0.6, 0.7, 1.0, 0.7). The application rates of N, P2O5, and K2O throughout the entire cotton growth period are... The application rate was 80% of that of the local traditional irrigation and fertilization methods. When determining the fertilization quota for a certain irrigation process during the seedling stage, bud stage, early flowering and boll formation stage, and late flowering and boll formation 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 the water and fertilizer integration technology, the fertilizer injection ratios before, during, and in the later stages of irrigation were 11%, 32%, and 57%, respectively, and chlormequat chloride was not sprayed throughout the entire growth period.

[0051] The results of the tests and demonstration applications show that:

[0052] 1) Compared with the traditional irrigation and fertilization method of spraying chlormequat chloride 6 to 8 times throughout the growth period, the application of the technology of this invention can effectively prevent cotton from growing too tall, even without chemical regulation. Furthermore, it can achieve the goals of water conservation, fertilizer conservation, salt suppression, yield increase, and income increase while maintaining the quality of cotton fibers. This proves that it is feasible to promote the efficient production of cotton using the technology of this invention under zero chemical control conditions.

[0053] 2) After screening, the optimal irrigation and fertilization technology model under zero chemical control conditions for drip irrigation under mulch film is as follows: water regulation coefficients for the seedling stage, bud stage, early flowering and boll-forming stage, and late flowering and boll-forming stage are 0.8, 0.9, 1.0, and 0.9, respectively; nutrient regulation coefficients are 0.6, 0.7, 1.5, and 0.7, respectively. Compared with traditional irrigation and fertilization methods, this technology model can save 10-17% of water, increase yield by 5-12%, and increase income by 10-28% while saving 20% ​​of fertilizer (e.g., ...). Figure 1 (As shown).

Claims

1. An irrigation and fertilization method for efficient production of cotton under zero-chemical regulation conditions, characterized by, The method comprises the following steps without spraying growth regulators: Setting a plant water deficit index threshold value, setting a water regulation coefficient according to the sensitivity of cotton at each growth stage to water stress; Optimizing the total amount of fertilization during the whole growth period of cotton, determining a nutrient regulation coefficient according to the sensitivity of cotton at each growth stage to nutrient stress; Continuously acquiring dynamic data of root zone soil water and salt, and evaluating the plant water deficit index; When the estimated value of the plant water deficit index is greater than the set threshold value, opening the valve to irrigate, calculating the irrigation quota according to the soil water content profile in the root zone before irrigation and the water regulation coefficient; According to the total amount of fertilization during the whole growth period and the aboveground dry matter accumulation curve, determining the initial value of the fertilization quota in each irrigation process, and then multiplying it by the nutrient regulation coefficient to obtain the fertilization quota; According to the irrigation quota, the fertilization quota and the irrigation area, determining the irrigation amount and the fertilization amount in each irrigation process respectively; Based on the amount of irrigation water, the irrigation process is divided evenly from beginning to end. n part( n ≥1), the cotton root zone is also divided from the maximum rooting depth to the ground surface. n The percentage of the area of ​​the closed loop of relative root length density corresponding to each segment from the maximum root depth to the ground surface is calculated as the percentage of the total area of ​​the root zone. This percentage is then used as the percentage of fertilization applied during each time period from the beginning to the end of the irrigation process. Specifically, the fertilization ratio corresponding to the first stage of irrigation is the percentage of the lowest root zone. n The percentage of the relative root length density of the segment; The water and fertilizer integration technology is used for synchronous fertilization during the irrigation process, and the fertilization amount at each irrigation stage is the product of the total fertilization amount in each irrigation process and the fertilization proportion at the stage; When the actual irrigation amount reaches the calculated value, stop irrigating, re-estimate the plant water deficit index and prepare for the next irrigation and fertilization; The cotton growth stages include seedling stage, squaring stage, pre-blossom stage, post-blossom stage and boll opening stage; During the seedling stage, squaring stage, post-blossom stage and boll opening stage, the water regulation coefficient is less than 1.0; During the pre-blossom stage, the water regulation coefficient is equal to or greater than 1.0, and increases with The soil salt content increases, and the water regulation coefficient increases; During the seedling stage, squaring stage, post-blossom stage and boll opening stage, the nutrient regulation coefficient is less than 1.0, The nutrient regulation coefficient during the post-blossom stage is determined according to the aboveground dry matter accumulation curve of cotton while keeping the total amount of fertilization during the whole growth period unchanged, The evaluation of the plant water deficit index threshold value is according to ; where is the water-salt stress recovery coefficient considering the stress hysteresis effect; is the water-salt stress cross-adaptation factor; h and are the soil water matric potential and osmotic potential (cm), respectively; and are the soil water and salt stress correction factors, respectively; z r is the relative soil depth, z r = z / L r is the soil depth (cm), L r is the crop root depth (cm); L nrd ( z r ) is the relative root length density distribution, obtained from equation (2): ; In the formula p is a root parameter, for cotton, p = 1.96; The irrigation quota is according to ; where I is the irrigation quota (m 3 / ha); β is the soil wetting ratio; R is the salt leaching coefficient; D w is the planned wetting depth (cm), generally taken as 60 cm; C w is the water regulation coefficient of cotton at each growth stage; The area of the relative root length density closed graph corresponding to each segment from the maximum root penetration depth to the ground surface accounts for a percentage of the total area of the root zone, which is calculated according to the relative root length density distribution graph shown in formula (2). f is the field water-holding capacity (cm 3 cm -3 ); ​ z is the soil water content at each depth before irrigation (cm 3 cm -3 ); and ​ is the field water use efficiency.​ 2. The method of claim 1, wherein the irrigation and fertilization method for high- efficiency production of cotton under zero-chemical regulation conditions is characterized by, ​

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