A method for fertilizing mature rubber trees based on nutrient cycling

Abstract

The application provides a mature rubber tree fertilization method based on nutrient circulation, which comprises the following steps: step one, establishing a relational expression Y i = litter decomposition + rainfall input + tree leaching + artificial fertilization; Y o = tree absorption + surface runoff; step two, using the soil nutrient balance principle, i.e. nutrient input Y i = nutrient output Y o , the above formula is brought into, and litter decomposition + rainfall input + tree leaching + artificial fertilization = tree absorption + surface runoff is obtained; step three, through nutrient calculation and data analysis, a function relationship between the recommended amount of fertilization Y f of the mature rubber tree and the tree age X is fitted, i.e. Y f =aX 2 +bX+c; the application solves the contradiction that the fertilization management does not meet the production demand caused by the problems such as single rubber tree fertilization formula, old diagnosis technology and difficult-to-determine test analysis index, and has good yield-increasing effect and production practicability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rubber tree planting, and particularly relates to a fertilization method for mature rubber trees based on nutrient cycling. BACKGROUND

[0002] Rubber is a typical economic crop and important strategic material in tropical regions, and plays an important role in maintaining the economic development and ecological system stability in hot regions. After years of rubber planting, although the rubber yield has been greatly improved, it has been at the cost of consuming a large amount of soil nutrients, and the gradual decline of soil fertility is a matter of concern. Especially in the long-term process of planting and production, due to unreasonable or excessive use of chemical fertilizers, the soil nutrient imbalance, soil acidification, low fertilizer utilization rate and high labor cost of rubber forest soil have restricted the sustainable development of the rubber industry.

[0003] Studies have shown that the fertilization measures based on the previous nutrient diagnosis method and standard do not fully consider the nutrient cycling process such as nutrient loss with tapping, return of litter nutrients, ignore the balance between nutrient demand and rubber production physiology, and cannot accurately predict the nutrient demand of rubber trees. In addition, the soil and leaf test data and field test quantity are insufficient, and a large amount of time and cost is needed in the process of collection and testing, the leaf nutrient diagnosis index is relatively old, the soil diagnosis formula is fixed and single, and a series of problems make it impossible to accurately and timely predict the nutrient balance in rubber forest soil, thereby causing the contradiction between rubber fertilization management and actual production needs.

[0004] Artificial economic forest is an open dynamic system, and a large amount of nutrients are taken away in the process of fruit harvesting and felling trees, which leads to the continuous decline of soil fertility and the imbalance of ecological system. Fertilization has become an important supplement to the nutrient balance in agricultural and forestry systems. In the past, the traditional method of fertilization management was mainly determined by experience, such as nutrient diagnosis fertilization and formula fertilization technology. Although it is practical in field production, it cannot meet the needs of precision agriculture and forestry development, especially for important economic forests such as rubber forest, and the fertilization of forest land needs to be more precise and targeted.

[0005] Therefore, it is an urgent problem to establish a scientific and reasonable current rubber tree fertilization method to realize high yield and soil fertilization of rubber trees. SUMMARY

[0006] To solve the above technical problems, the present application analyzes soil nutrient surplus and deficiency according to the soil balance principle, combines the input and output sources of nutrients in the rubber forest ecosystem nutrient cycle, deduces the nutrient demand of rubber forests of different ages, establishes a rubber tree fertilization estimation model, and formulates fertilization formulas for rubber trees of different strains and different ages, so as to achieve the purpose of reasonable and scientific fertilization of rubber trees and the technical effect of sustainable yield increase and yield stability of rubber.

[0007] The present application provides a mature rubber tree fertilization method based on nutrient cycle, which is based on the nutrient cycle law of rubber forest ecosystem, the soil nutrient balance principle, and the correlation between rubber forest nutrient demand and physiological growth, establishes a functional relationship between the fertilization estimation amount of different strains of rubber trees and the age of the trees to determine the recommended amount of rubber tree fertilization, specifically including the following steps:

[0008] Step one, according to the input and input sources of nutrients in the nutrient cycle of rubber forest ecosystem, the input Y i of rubber forest nutrients and the output Y o relationship are established respectively,

[0009] Formula (1): Y i = litter decomposition + rainfall input + tree leaching + artificial fertilization;

[0010] Formula (2): Y o = tree absorption (including litter and latex) + surface runoff;

[0011] Step two, using the soil nutrient balance principle, i.e. formula (3): nutrient input Y i = nutrient output Y o ; formula (1) and formula (2) are brought into formula (3) to establish the soil nutrient balance formula of rubber forest, which is

[0012] Formula (4): litter decomposition + rainfall input + tree leaching + artificial fertilization = tree absorption (including litter and latex) + surface runoff;

[0013] Step three, through nutrient estimation and data analysis, it is found that there is a highly significant correlation (p<0.01) between the estimated amount of rubber tree fertilization and the age of the rubber tree, and the function relationship between the recommended amount of fertilization Y f of mature rubber trees and the age X is fitted, and the rubber tree fertilization model is obtained, i.e.

[0014] Formula (5): Y f = aX 2 +bX+c, 6≤X≤40, for mature rubber trees.

[0015] Preferably, the strain of the rubber tree is RRIM600 strain and PR107 strain,

[0016] The RRIM600 strain fertilization model is as follows:

[0017] Nitrogen: y = -1.2856X 2 + 61.970X - 123.950;

[0018] Phosphorus: y = -0.1228X 2 + 6.4290X - 14.2864;

[0019] Potassium: y = -0.7276X 2 + 35.946X + 13.4020;

[0020] Calcium: y = -0.7135X 2 + 36.215X - 44.932;

[0021] Magnesium: y = -0.1158X 2 + 5.7371X - 1.7961;

[0022] The PR107 strain fertilization model is as follows:

[0023] Nitrogen: y = -1.2407X 2 + 51.208X - 66.314;

[0024] Phosphorus: y = -0.1317X 2 + 5.6969X - 18.3910;

[0025] Potassium: y = -0.5138X 2 + 23.080X - 5.0953;

[0026] Calcium: y = -0.5698X 2 + 25.951X + 19.643;

[0027] Magnesium: y = -0.1182X 2 + 4.9636X - 3.7676.

[0028] The present application has the following advantages:

[0029] The present application is based on the nutrient circulation law of rubber forest ecosystem, the soil nutrient balance principle, and the correlation between the nutrient demand and physiological growth of rubber trees, establishes a functional relationship between the fertilization estimation amount of different strains of rubber trees and the tree age, and takes the tree age as the only index to calculate the reasonable fertilization amount of the current rubber trees, solves the contradiction between the fertilization management and the production demand caused by the single fertilization formula of rubber trees, the old diagnosis technology, and the difficulty in determining the test analysis index, and has good yield-increasing effect and production practicability. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below only illustrate a part of the embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative effort based on the drawings provided are within the scope of protection of the present application.

[0031] Figure 1 Schematic diagram of nutrient cycle in rubber forest ecosystem;

[0032] Figure 2 Yield comparison of rubber tree of RRIM600 strain;

[0033] Figure 3 Yield comparison of rubber tree of PR107 strain. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0035] As shown in Figure 1 , the nutrient cycle in rubber forest ecosystem mainly includes external nutrient input, external nutrient output and internal nutrient cycle. The external nutrient output approaches mainly include tapping and moving away, surface runoff, underground leakage, N volatilization, etc. The external nutrient input approaches mainly include rainfall, artificial fertilization and biological nitrogen fixation, etc. The internal nutrient cycle process mainly includes that the soil nutrients in the rubber plantation are absorbed into the rubber tree body, the rubber tree stores and redistributes the nutrients through assimilation, part of the nutrients remains in the body to meet the growth and rubber production, part of the nutrients is transferred to the fallen branches and leaves to decompose and release to the soil, and a small part of the nutrients is excreted from the tree organs and returned to the soil through rainwater leaching.

[0036] Embodiment 1

[0037] The nutrient input items in the rubber forest ecosystem mainly include: ① nutrients released by litter decomposition. The rubber forest is a perennial tall tree, which forms periodic leaf fall all year round, and more than 70% of the litter can be decomposed to release nutrients to the soil every year. ② A small part of nutrients brought by rainfall. ③ nutrients leached by tree body. The nutrients excreted by the tree organs of the rubber tree are returned to the soil through rainwater leaching. ④ nutrients brought by fertilization. ⑤ biological nitrogen fixation. Legume plants are planted under the rubber forest, and biological nitrogen fixation is used to absorb nitrogen from the air.

[0038] In addition, the short-term plants under the rubber forest form a nutrient internal cycle by absorbing and returning to the soil. The adsorption and release of nutrients by soil colloids also belong to the internal cycle. Because of the complex mechanism of nutrient transfer, the effective nutrients released by the soil are not considered.

[0039] Therefore, the input of nutrients Y i The relationship can be expressed as follows:

[0040] Equation (1): Y i = litter decomposition + rainfall input + tree leaching + artificial fertilization;

[0041] The output of nutrients in the rubber forest ecosystem mainly includes: ① nutrients absorbed by rubber trees, including tree retention nutrients, litter nutrients, and latex nutrients. ② nutrients in surface runoff, which will take away a small part of nutrients outside the rubber forest when the rainfall is large. ③ nutrients in surface evaporation and underground seepage.

[0042] Because the surface plant coverage density of the rubber forest is large, it limits the nutrients being taken to the air due to the water evaporation process, so surface evaporation is not considered. The surface runoff speed of the rubber forest far exceeds the underground seepage speed, so the nutrients taken away by underground seepage are not considered.

[0043] Therefore, the output of nutrients Y o The relationship can be expressed as follows:

[0044] Equation (2): Y o = tree absorption (including litter and latex) + surface runoff;

[0045] The balance relationship of soil nutrients in the rubber forest is:

[0046] Equation (3): Nutrient input Y i = nutrient output Y o ;

[0047] Substituting (1) and (2) into equation (3), we get

[0048] Equation (4): Litter decomposition + rainfall input + tree leaching + artificial fertilization = tree absorption (including litter and latex) + surface runoff;

[0049] Further derivation of equation (4) gives the relationship of the rubber tree fertilization amount Y f as:

[0050] Equation (5): Y f = tree absorption (including litter and latex) + surface runoff - litter decomposition - rainfall input - tree leaching

[0051] 6-37 years old rubber tree nitrogen, phosphorus, potassium, calcium, magnesium total nutrient uptake was 521.31-1743.24 kg / hm 2 , the amount of total nutrients released by litter decomposition was 123.34-321.15 kg / hm 2 , the amount of total nutrients in tree trunk leaching was 0.0356-3.8035 kg / hm 2 , the difference between the nutrients input by rainfall and surface runoff in hydrological cycle was between-0.0951-6.0208 kg / hm 2 .

[0052] Therefore, it can be seen that the absorption of rubber tree and the return of litter decomposition to a large extent determine the nutrient demand of rubber tree.

[0053] Through equation fitting, the coupling relationship between tree absorption and litter decomposition and tree age in equation (5) showed a quadratic function trend, so this study can use a quadratic equation to fit the correlation between rubber tree fertilizer application and tree age, and the correlation analysis between rubber tree fertilizer application Y f and tree age (X) reached a very significant level (P<0.01).

[0054] Equation (6): Y f =aX 2 +bX+c;

[0055] In view of the different demand rules of different strains of rubber trees for various nutrient elements in the process of physiological growth, leading to differences in absorption and utilization of nutrients in different growth stages of rubber trees. Through Excel 2016 software, the measured fertilizer application of RRIM600 strain between 6-38 years old and PR107 strain between 7-38 years old was fitted by a quadratic function, and the recommended model of rubber tree fertilizer application of RRIM600 and PR107 two major strains (6-40 years old) was obtained, as shown in Table 1:

[0056] Table 1

[0057]

[0058] As can be seen from Table 1, tree age is not only an important factor for determining the nutrient demand of rubber tree, but also a unique parameter that can be used to conveniently and directly calculate the fertilizer demand of rubber tree in different age groups.

[0059] The maximum recommended fertilizer application of different strains of rubber trees and tree age can be calculated from the fertilizer application model in Table 1: through the recommended fertilizer application model (quadratic function) of each element N, P, K, Ca, Mg of RRIM600 strain in Table 1, the maximum fertilizer application corresponding to the highest point of the function curve of each element was obtained as N 622.83 kg / hm 2 , P 69.21 kg / hm2 , K 457.37 kg / hm 2 , Ca 414.61 kg / hm 2 , Mg 69.26 kg / hm 2 The sum of the maximum fertilization amounts of all elements is calculated to be about 1633.29 kg / hm for the RRIM600 strain 2 The maximum nutrient requirement is at the age of 24 years. Similarly, the maximum fertilization amounts of each element corresponding to the highest point of the function curve are obtained by the recommended fertilization model (quadratic function) of each element N, P, K, Ca, and Mg in the PR107 strain in Table 1, and the maximum fertilization amounts are N 462.07 kg / hm 2 , P 43.22 kg / hm 2 , K 254.09 kg / hm 2 , Ca 315.12 kg / hm 2 , Mg 48.34 kg / hm 2 The sum of the maximum fertilization amounts of all elements is calculated to be about 1122.84 kg / hm for the PR107 strain 2 The maximum nutrient requirement is at the age of 21 years.

[0060] The maximum fertilization amount and the age with the maximum nutrient requirement calculated by the model are basically consistent with the existing research, indicating that the fertilization recommendation model is scientific and solves the problems of heavy testing workload and uncertainty of indicators in the past, and therefore has high operability and practicality.

[0061] Test Example 1

[0062] A piece of field in Xilian, Xiqing Farm, and Experimental Farm of the Hainan Academy of Agricultural Sciences in Danzhou City, Hainan Province was selected. The field is a granite developed laterite with vegetation coverage under the forest, no legume plants, and flat terrain. The test objects were RRIM600 strain rubber trees at the ages of 9, 12, 17, 25, 27, and 31 years, and PR107 strain rubber trees at the ages of 10, 15, 19, 21, 27, and 31 years.

[0063] The plant spacing of each age of rubber tree plantation was 3 m, the row spacing was 7 m, and the number of trees was about 450 tree / hm 2 The tapping system was s / 2˙d / 3.

[0064] After applying the rubber tree fertilization recommendation model, the results were compared with conventional fertilization, as shown in Tables 2, 3, and Figure 2 , Figure 3 .

[0065] From Figure 2 and Figure 3It can be seen that the recommended fertilization significantly improves the dry rubber yield of rubber trees, and the average single plant dry rubber yield of the RRIM600 strain is increased by 0.56 kg, the per mu yield is increased by 16.65 kg, the average single plant dry rubber yield of the PR107 strain is increased by 0.92 kg, and the per mu yield is increased by 27.70 kg, and the difference between the two fertilizations is analyzed, and both reach extremely significant (P<0.01).

[0066] Table 2

[0067]

[0068] Table 3

[0069]

[0070] Test Example 1 shows that the rubber tree fertilization recommendation model and method based on the nutrient circulation law of rubber forest ecosystem and the soil nutrient balance principle, with tree age as the key parameter to calculate the recommended amount of fertilization of different elements for different strains of rubber trees at different ages, not only conforms to the objective law of nutrient utilization of rubber trees at different growth stages, but also solves the problems of heavy testing work and uncertainty of indicators in actual work. After the actual production verification, it has obvious yield-increasing effect and can well guide the rubber tree fertilization management.

[0071] The above description of disclosed embodiments enables those skilled in the art to carry out or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A fertilization method for mature rubber trees based on nutrient cycling, characterized in that, Includes the following steps: Step 1: Based on the nutrient inputs and sources in the nutrient cycle of the rubber forest ecosystem, establish the nutrient input Y0 for the rubber forest. i Nutrient output Y o Relationship, Formula (1): Y i =Decomposition of litter + Rainfall input + Tree leaching + Artificial fertilization; Formula (2): Y o =Tree absorption + Surface runoff; Step two, utilizing the principle of soil nutrient balance, namely... Equation (3): Nutrient input Y i =Nutrient Output Y o ; Substituting equations (1) and (2) into equation (3), we get Equation (4): Decomposition of litter + Rainfall input + Tree leaching + Artificial fertilization = Tree absorption + Surface runoff; Step 3: Through nutrient measurement and data analysis, a highly significant correlation was found between the estimated fertilizer application rate for rubber trees and tree age. Furthermore, a recommended fertilizer application rate Y for mature rubber trees was fitted. f The functional relationship between the tree age X and the tree's age X leads to a fertilization model for rubber trees, namely... Formula (5): Y f =aX 2 +bX+c, 6≤X≤40, indicates a mature rubber tree; The rubber tree varieties are RRIM600 and PR107. The fertilization model for the RRIM600 strain is as follows: Nitrogen: y = -1.2856X 2 +61.970X-123.950; Phosphorus: y = -0.1228X 2 +6.4290X-14.2864; Potassium: y = -0.7276X 2 +35.946X+13.4020; Calcium: y = -0.7135X 2 +36.215X-44.932; Magnesium: y = -0.1158X 2 +5.7371X-1.7961; The fertilization model for the PR107 strain is as follows: Nitrogen: y = -1.2407X 2 +51.208X-66.314; Phosphorus: y = -0.1317X 2 +5.6969X-18.3910; Potassium: y = -0.5138X 2 +23.080X-5.0953; Calcium: y = -0.5698X 2 +25.951X+19.643; Magnesium: y = -0.1182X 2 +4.9636X-3.7676.

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