Fertilization method for combined application of straw carbonized biochar and inorganic nitrogen fertilizer

Abstract

The invention belongs to the technical field of agricultural planting fertilizer application, and relates to a fertilization method for combined application of straw carbonized biochar and an inorganic nitrogen fertilizer. According to the fertilizing method, biochar prepared by pyrolysis of corn straw is used as a main fertilizer and is matched with a nitrogen fertilizer and a phosphate fertilizer, the biochar is applied at a time before sowing when spring corn is planted in the first year, and the biochar is applied according to the adding amount of the biochar which is larger than 0 and smaller than or equal to 15 t ha <-1 >. According to the fertilization method, the utilization efficiency of straw is effectively improved, the soil structure is improved, and the corn yield is increased by applying the charcoal and the inorganic nitrogen fertilizer.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural planting fertilizer application, and relates to a fertilization method of combining straw carbonized biochar with inorganic nitrogen fertilizer. Background Art

[0002] With the continuous increase in population, in order to meet people's demand for food, the global planting area of ​​grain crops continues to expand, and the amount of crop straw produced has also increased significantly. Due to its own difficult-to-degrade characteristics, straw cannot be applied in large quantities in the soil, and in the process of anaerobic decomposition, it needs to absorb nitrogen and other elements from the soil. Too much return to the field can easily cause nitrogen deficiency, and improper decomposition can also lead to an increase in toxic and harmful gases such as methane and hydrogen sulfide. How to efficiently utilize straw resources, accelerate the virtuous cycle of straw resource development and utilization, reduce air pollution caused by open-air burning of straw, promote economic and ecological coordination and sustainable development, and improve agricultural production efficiency has become a key issue that needs to be solved urgently.

[0003] In recent years, research on biochar has been very hot. Biochar is a solid product produced by thermal cracking of biological straw in anoxic or anaerobic environment. It has the characteristics of being porous, large specific surface area, strong adsorption capacity, and strong carbon stability. It can increase the content of soil organic matter, promote nutrient utilization, improve soil structure and soil water retention capacity, and effectively increase crop yields.

[0004] Studies have found that the physical and chemical properties of biochar determine its effect on soil improvement, and its properties are closely related to its carbonization process. Different preparation processes (including pyrolysis heating method, pyrolysis temperature, cracking time, etc.) lead to differences in the properties and characterization of biochar. At present, research on the effect of pyrolysis temperature on the physical and chemical properties of biochar needs to be further explored.

[0005] A large number of studies have shown that the addition of exogenous biochar can improve the nitrogen loss caused by excessive nitrogen fertilizer application, such as leaching and runoff, as well as eutrophication and greenhouse gas emissions. However, some studies have shown that when the application rate exceeds a certain level, the loss of nutrients will be accelerated due to excessive soil voids, significantly inhibiting the formation of soil aggregates and the growth of microorganisms. This shows that the reasonable application of biochar according to local conditions is the key to improving soil fertility and increasing plant nutrient utilization efficiency.

[0006] At the same time, in order to increase the yield of grain crops, farmers generally apply excessive fertilizers, which leads to a sharp decline in the nitrogen utilization efficiency of farmland, thus aggravating the environmental problems. Therefore, it is very important to develop an efficient fertilization plan for the combination of straw and fertilizers. Summary of the invention

[0007] The purpose of the present invention is to provide a fertilization method of straw carbonized biochar combined with inorganic nitrogen fertilizer, which can improve the utilization efficiency of straw, improve soil structure and increase corn yield.

[0008] The technical solution of the present invention to solve the above technical problems is as follows.

[0009] A fertilization method of straw carbonized biochar combined with inorganic nitrogen fertilizer uses biochar prepared by pyrolysis of corn straw as a main fertilizer, combined with nitrogen fertilizer and phosphorus fertilizer, and applies biochar once before sowing when planting spring corn in the first year.

[0010] Furthermore, the fertilization method comprises the following steps:

[0011] (1) According to 0<biochar addition ≤15 t ha -1 The biochar is applied in an amount of 10 t ha, which is applied once before corn planting in the first year and no longer applied in the second year. -1 ;

[0012] (2) Based on 150-300 kg N ha -1 Nitrogen fertilizer is applied at a rate of 225 kg N ha -1 ;

[0013] (3) 80-100 kg ha -1 Apply phosphorus fertilizer at the bottom, but not potassium fertilizer;

[0014] (4) Biochar and nitrogen fertilizer were sprinkled on the soil surface in the first year and tilled into the 20 cm soil layer using a rotary tiller;

[0015] (5) The planting density of spring corn is 5400 plants / mu to 5700 plants / mu, the plant spacing is 20cm-25cm, and the row spacing is 48cm-52cm.

[0016] Furthermore, in the fertilization method, the biochar is prepared from corn stalks at a pyrolysis temperature of 490°C-510°C; preferably, the pyrolysis temperature is 500°C.

[0017] Furthermore, in the fertilization method, nitrogen fertilizer is mixed in a ratio of 3:7 between conventional urea and controlled-release urea.

[0018] Furthermore, this fertilization method is suitable for the cultivation and fertilization of dryland corn in the Loess Plateau, that is, the Loess Plateau region with insufficient total precipitation, poor soil and low organic matter content.

[0019] The beneficial effect of the fertilization method of straw carbonization biochar combined with inorganic nitrogen fertilizer of the present invention is that, by adding biochar as a soil conditioner and utilizing the physical and chemical properties of biochar itself, on the one hand, it is beneficial to the improvement of soil structure and the fixation of organic matter, improves the soil nutrient content, promotes nutrient release and plant absorption, reduces nutrient loss, and increases corn yield; on the other hand, it can improve the utilization efficiency of straw resources and nitrogen fertilizer, and plays a good role in ecological environment and resource utilization. In particular, for the problems of insufficient total precipitation, poor soil, low organic matter content, and rich crop straw resources but low resource utilization in the Loess Plateau, the straw carbonization and field return and high-efficiency fertilizer combined with soil carbonization and fertilization technology are carried out in combination with cultivation management technology, so as to provide efficient fertilization technology for dryland corn production in the region; the optimal corn straw biochar pyrolysis temperature is selected, and the fertilization method of combining with inorganic nitrogen fertilizer is used to improve the utilization efficiency of straw and nitrogen fertilizer, reduce the application of nitrogen fertilizer, and achieve the effect of soil improvement and yield increase; the fertilization method of the present invention has the advantage of lasting fertilizer effect, and has wide applicability and promotion space. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figures 1 to 3 The electron microscope scanning images of biochar at pyrolysis temperatures of 300℃, 500℃, and 800℃ respectively;

[0021] Figure 4 The dry matter accumulation of spring corn under different biochar addition amounts and nitrogen application rates;

[0022] Figure 5 is the total nitrogen content under different biochar addition amounts and nitrogen application rates;

[0023] Figure 6 Soil organic matter under different biochar addition and nitrogen application rates;

[0024] Figure 7 Spring corn yield under different biochar addition amounts and nitrogen application rates. DETAILED DESCRIPTION

[0025] 1. Trial location

[0026] This experiment was conducted at the Changwu Loess Plateau Agricultural Ecological Experimental Station of the Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources. The experimental field is located in Wangdong Village, Hongjia Town, Changwu County, Xianyang City, Shaanxi Province (35.28°N, 107.88°E). The base is located in the central and southern part of the Loess Plateau at the junction of Shaanxi and Gansu. It has a continental monsoon climate, with an altitude of 1200m, an average sunshine of about 2226.5h, a frost-free period of about 171d, an average annual temperature of 9.1℃, an active accumulated temperature ≥10℃ of 3029.1℃, an average annual precipitation of 580mm, and a groundwater level of 50-80m.

[0027] The main source of water in the test site is precipitation, which is unevenly distributed, with more precipitation in summer and less precipitation in winter, concentrated in July-September. It is a typical dryland agricultural area. The soil in the test site is black loam soil, and the physical and chemical properties of the soil in the 0-20cm soil layer are organic matter 14.71 g kg -1 , fast-acting nitrogen 7.56 mg kg -1 Total nitrogen 0.91 g kg -1 , available phosphorus 14.4 mg kg -1 , fast-acting potassium 148.5 mg kg -1 , pH 7.9, bulk density 1.3 g cm -3 .

[0028] 2. Experimental plan

[0029] Three biochars with different pyrolysis temperatures were selected, including 300℃, 500℃, and 800℃. The optimal biochar pyrolysis temperature was determined by measuring the elemental composition of the biochar and scanning with an electron microscope.

[0030] Under this premise, set 0 t ha -1 (B0)、5 t ha -1 (B5), 10 t ha -1 (B10) and 15 t ha -1 (B15) Four biochar addition amounts, applied once to the field before corn planting in 2022, and no application in the second year.

[0031] Nitrogen fertilizer was applied by mixing conventional urea and controlled-release urea in a ratio of 3:7, and the conventional nitrogen application rate was set at 300 kg Nha. -1 (N0), 25% reduction is 225 kg N ha -1 (N2) and a 50% reduction of 150 kg N ha -1 (N5) Three nitrogen fertilizer gradients, applied once before corn planting each year, including controlled-release urea (N≥28%) and conventional urea (N≥46%).

[0032] There are 12 treatments in total, with three replicates for each treatment, and the plot area is 28m 2 (4m×7m).

[0033] Phosphate fertilizer was applied to each treatment, 90 kg ha -1 (P2O5≥16%), no potassium fertilizer is applied.

[0034] The planting density of spring corn is 5,500 plants / mu, plant spacing: 23.3 cm, row spacing: 50 cm.

[0035] After planting, spring corn was managed according to local routine field management measures. The experiment was carried out for two consecutive years. Plant and soil samples were collected during the critical period of corn to measure plant growth, soil moisture and nutrients, as well as corn yield and nitrogen fertilizer use efficiency.

[0036] 3. Determination methods of project-related indicators

[0037] a. Biochar related indicators

[0038] Element content: The carbon and nitrogen contents in the carbonized biochars of corn straw at different pyrolysis temperatures were determined using an element analyzer, as shown in the following table.

[0039] Pyrolysis temperature / ℃ C / % N / % C / N 300 0.42 14.83 35.63 500 0.81 34.30 42.59 800 0.84 35.39 41.96

[0040] Scanning electron microscope: The biochar powder was scanned and photographed using an electron microscope to observe the microscopic morphology of the biochar surface, such as Figures 1 to 3 Shown are electron microscope scanning images of biochar at different pyrolysis temperatures.

[0041] b. Determination of soil related indicators

[0042] Soil moisture: Soil augers were used to take samples from 0-200 cm for each treatment, with each 20 cm layer consisting of 10 soil layers in total. Each treatment was repeated three times and the samples were measured using the drying method.

[0043] Soil nutrient determination: Soil samples were collected after corn harvest, and the soil organic carbon content was determined by potassium dichromate external heating method, and total nitrogen was determined by Kjeldahl digestion method (determined on AA3 flow analyzer).

[0044] c. Determination of plant-related indicators

[0045] Plant samples were collected during the critical growth period of corn, dried at 105°C, and the dry matter accumulation of corn under different biochar addition and nitrogen application rates was determined by weighing method (e.g. Figure 4 ), and total nitrogen content (e.g. Figure 5 ), soil organic matter (such as Figure 6 ), spring corn yield (such as Figure 7 ).

[0046] 4. Results Analysis

[0047] From the previous table and Figures 1 to 3 It can be seen that with the increase of pyrolysis temperature, the carbon, nitrogen content and carbon-nitrogen ratio of biochar all show an increasing trend. There is no significant difference under 500 and 800℃ pyrolysis conditions. Combined with the electron microscope scanning image, the biochar under 500℃ pyrolysis condition has a richer pore structure, which can provide more adsorption points. In summary, the use of biochar at 500℃ pyrolysis temperature has a better effect on soil improvement.

[0048] Depend on Figures 4 to 7 It can be seen that adding 10 t ha -1 Biochar combined with 225 kg N ha -1 Under the treatment, the biomass and yield of spring maize were the best, and the yield reached 12879.72 kg ha -1 ; Adding biochar can also increase the content of organic matter and total nitrogen in the soil, with 15 t ha -1 The organic matter content was the highest when biochar was added, and 10 t ha -1 The total nitrogen content in soil was the highest when biochar was added.

Claims

1. A fertilization method for applying straw carbonized biochar with inorganic nitrogen fertilizer, characterized in that: Biochar made from pyrolysis of corn straw is used as the main fertilizer, combined with nitrogen fertilizer and phosphorus fertilizer, and biochar is applied once before sowing when planting spring corn in the first year.

2. The fertilization method according to claim 1, characterized in that: The steps include: (1) According to 0<biochar addition ≤15 t ha -1 Biochar was applied in an amount of , which was applied once before corn planting in the first year, and no application was done in the second year; (2) 150-300 kg N ha -1 Nitrogen fertilizer is applied at a rate of 1000 N / m, and the method of application is a one-time application before corn planting each year; (3) 80-100 kg ha -1 Apply phosphorus fertilizer at the bottom, but not potassium fertilizer; (4) Biochar and nitrogen fertilizer were sprinkled on the soil surface in the first year and tilled into the 20 cm soil layer using a rotary tiller; (5) The planting density of spring corn is 5400 plants / mu to 5700 plants / mu, the plant spacing is 20cm-25cm, and the row spacing is 48cm-52cm.

3. The fertilization method according to claim 2, characterized in that: The biochar is prepared by pyrolyzing corn stalks at a temperature of 490° C. to 510° C.

4. The fertilization method according to claim 2, characterized in that: The nitrogen fertilizer is mixed with conventional urea and controlled-release urea in a ratio of 3:

7.

5. The fertilization method according to claim 2, characterized in that: It is suitable for planting and fertilizing dryland corn in the Loess Plateau.

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