Method for improving quality and increasing yield of red soil rice field based on woody peat composite improvement

Abstract

The invention discloses a quality-improving and yield-increasing method for a red soil rice field based on composite improvement of woody peat, which aims at solving the problems of acidification, hardening, low organic matter and high methane emission intensity of the red soil rice field, and comprises the following steps: deeply applying woody peat, lime and wormcast into a plough layer before transplanting; humic acid of woody peat and lime calcium ions are utilized to form a stable cement, acid is adjusted for a long time, aggregate formation is promoted, and active flora in wormcast accelerates carbon source activation; secondly, wet straw covering is conducted between rows after transplanting, intermittent irrigation is combined, and the microbial metabolism path of the waterlogged soil is directionally regulated and controlled through the synergistic effect of covering and woody peat release substances. By means of the method, the pH value of the red soil rice field can be stably increased to a suitable range, soil organic matter is remarkably increased, the rice yield is increased by 8%-15%, meanwhile, the rice quaternary methane emission intensity is reduced by 20%-30%, cooperation of rapid soil improvement, crop yield increase and quality improvement and greenhouse gas emission reduction is achieved, benefits are remarkable, and environment friendliness is achieved.

Description

Technical Field

[0001] This invention belongs to the field of agricultural soil improvement and paddy field ecological management technology, specifically involving a method for improving the quality and increasing the yield of red soil paddy fields based on woody peat composite improvement. Background Technology

[0002] Red soil paddy fields are widespread in southern my country, but due to long-term intensive use, acid deposition, and irrational fertilization, they generally suffer from prominent problems such as soil acidification (pH often below 5.5), low organic matter content, soil compaction, aluminum and manganese toxicity, and poor water and fertilizer retention capacity. These factors severely restrict the improvement of rice yield and rice quality.

[0003] Currently, most improvement measures for red soil paddy fields are single-method approaches, such as: applying lime to quickly adjust acidity, but the effect is not lasting and easily leads to soil compaction; increasing the application of ordinary organic fertilizers (such as livestock and poultry manure) to increase organic matter, but the effect on improving soil structure and alleviating aluminum toxicity is limited, and there may be risks of introducing heavy metals and antibiotics; although returning straw to the field can supplement carbon sources, it decomposes slowly in the acidic environment of red soil, easily producing organic acids and aggravating acidification. Summary of the Invention

[0004] The purpose of this invention is to overcome the one-sidedness and limitations of existing red soil paddy field improvement technologies and provide a method for improving the quality and increasing the yield of red soil paddy fields based on woody peat composite improvement. This method takes woody peat as the core and innovatively combines and applies it in synergistic ways with agricultural lime, earthworm castings, and rice straw mulching techniques to form a four-in-one composite improvement system of "rapid acidification, long-term carbon increase, structural improvement, and ecological regulation".

[0005] A method for improving the quality and increasing the yield of red soil paddy fields based on woody peat composite improvement includes the following steps: Step S1: Base fertilizer application and initial soil mixing: Before rice transplanting, apply agricultural lime and air-dried and crushed woody peat as base fertilizer to the field surface, followed by shallow tillage. Step S2: Deep application of organic fertilizer and harrowing: After shallow plowing, spread the decomposed earthworm castings evenly on the field surface, then irrigate the field and perform deep rotary tillage or water harrowing to ensure that all base materials are fully integrated with the topsoil. Step S3: Straw mulching and water management: After rice transplanting, chopped rice straw is evenly mulched on the field surface between rice rows, and intermittent irrigation is implemented during the rice tillering stage.

[0006] Preferably, in step S1, the amount of agricultural lime applied is determined based on the initial pH and texture of the target topsoil. When the soil pH is ≤5.0 and the soil is sandy or loam, the amount of agricultural lime applied is 750-1500 kg / ha; when the soil is clay, the amount of agricultural lime applied is 1500-2250 kg / ha. When the soil pH is 5.0 < ≤5.5 and the soil is sandy or loam, the amount of agricultural lime applied is 750-1125 kg / ha; when the soil is clay, the amount of agricultural lime applied is 1125-1875 kg / ha. When the soil pH is 5.5 < ≤6.0 and the soil is sandy or loam, the amount of agricultural lime applied is 375-750 kg / ha; when the soil is clay, the amount of agricultural lime applied is 750 kg / ha.

[0007] Preferably, the amount of woody peat used is 2.0-3.0 tons / hectare, the particle size is ≤5mm, and the depth of shallow tillage is 12-15cm.

[0008] Preferably, in step S2, the amount of decomposed earthworm castings used is 3.0-4.5 tons / hectare; and the depth of deep rotary tillage or water harrowing is 18-20 cm.

[0009] Preferably, the amount of rice straw used for mulching is 2.5-3.5 tons / hectare by dry weight, and the chopped length is 10-15cm; the intermittent irrigation mode is a cycle of "shallow water layer - natural drying - field drying".

[0010] Preferably, the method further includes step S4: during the peak tillering and booting stages of rice, foliar spraying of water-soluble fertilizer containing trace elements such as silicon and zinc is performed 1-2 times.

[0011] The beneficial effects of this invention are: 1. Synergistic soil improvement with comprehensive and lasting effects: It can quickly raise and stabilize the pH value of red soil paddy fields within the suitable range of 5.8-6.5, while significantly increasing soil organic matter content, reducing soil bulk density, and improving the structure of the topsoil. The overall effect far exceeds that of applying a single material.

[0012] 2. Significantly increases yield and improves quality: It can effectively promote the development of rice roots and nutrient absorption, and increase yield components such as the number of effective panicles and the weight of a thousand grains in a synergistic manner, achieving an increase in yield per mu of 8%-15%; at the same time, it improves rice quality, reduces chalkiness, and increases the head rice rate.

[0013] 3. Optimize paddy field ecology and reduce emissions and carbon sequestration: Significantly enhance soil microbial diversity and enzyme activity, promoting the proliferation of beneficial microbial communities (such as ammonia-oxidizing bacteria and silicate-solubilizing bacteria). The unique material combination can regulate the carbon metabolism pathway of flooded soil, effectively reducing methane (CH4) emission intensity by 20%-30%, achieving a synergistic effect of increased production and emission reduction.

[0014] 4. Environmentally friendly and resource-recycling: Make full use of natural or recycled resources such as woody peat, earthworm castings, and straw, avoid the potential environmental risks of chemical amendments, reduce dependence on chemical fertilizers, and conform to the development direction of green and low-carbon agriculture. Attached Figure Description

[0015] Figure 1 A comparison chart of soil organic matter content; Figure 2 A comparison chart of soil pH values; Figure 3 This is a comparison chart of nitrogen, potassium, and phosphorus content; Figure 4 Factors influencing rice yield and overall yield; Figure 5 The cumulative methane emissions and emission intensity during the rice growing season; Figure 6 This represents the relative abundance of soil microorganisms. Detailed Implementation

[0016] To achieve the above objectives, the present invention adopts the following technical solution: A method for improving the quality and increasing the yield of red soil paddy fields based on woody peat composite improvement includes the following steps: 1. Base Fertilizer Application and Initial Soil Mixing: 7-10 days before rice transplanting, apply agricultural lime (CaO≥85%) and air-dried, pulverized woody peat (particle size≤5mm) as base fertilizer to the field surface in one application. The amount of agricultural lime applied is determined based on the initial pH and texture of the target topsoil, and is 75% of the theoretical amount of lime required to raise the soil pH to 5.8-6.2. Specifically, when the soil pH is ≤5.0 and the soil is sandy or loam, the application rate of agricultural lime is 750-1500 kg / ha; when the soil is clay, the application rate is 1500 kg / ha. -2250 kg / ha; when soil pH is 5.0 < ≤ 5.5, and the soil is sandy or loam, the application rate of agricultural lime is 750-1125 kg / ha, and when the soil is clay, the application rate of agricultural lime is 1125-1875 kg / ha; when soil pH is 5.5 < ≤ 6.0, and the soil is sandy or loam, the application rate of agricultural lime is 375-750 kg / ha, and when the soil is clay, the application rate of agricultural lime is 750 kg / ha.

[0017] When the main component of the lime used is hydrated lime [Ca(OH)2], the amount used needs to be multiplied by a coefficient of 0.74.

[0018] The application rate of woody peat is 2.0-3.0 tons / hectare. After application, shallow tillage (12-15cm deep) should be carried out immediately to allow the material to be initially mixed with the topsoil.

[0019] 2. Deep application and harrowing of organic fertilizer: After shallow tillage, evenly spread well-rotted earthworm castings on the field surface at a rate of 3.0-4.5 tons / hectare. Then irrigate the field and perform rotary tillage or water harrowing to a depth of 18-20cm to ensure that the woody peat, lime, and earthworm castings are fully and evenly integrated with the topsoil.

[0020] 3. Straw Mulching and Water Management: After rice transplanting, evenly cover the exposed water surface between the rice rows with the previous season's rice straw (chopped to 10-15cm in length), with a mulch volume of 2.5-3.5 tons / hectare (dry weight). During the rice tillering stage, implement an intermittent irrigation pattern of alternating shallow water, moistening, and drying to avoid prolonged deep water flooding.

[0021] 4. Topdressing: During the peak tillering and booting stages of rice, apply water-soluble fertilizer containing silicon and zinc as a foliar spray 1-2 times, in conjunction with green pest and disease control.

[0022] Innovation points: 1. Material Compatibility and Functional Synergistic Innovation: For the first time, a ternary composite basal application system was constructed, consisting of "woody peat (long-lasting carbon increase and acid adjustment) - agricultural lime (rapid neutralization of acidity) - earthworm castings (promoting growth and improving soil structure)". The humic acid in woody peat combines with calcium ions in lime to form a stable "humic acid-calcium" cement, which can buffer pH fluctuations and promote the formation of soil aggregates. The large number of beneficial microorganisms and their secretions in earthworm castings accelerate the activation and utilization of the stable carbon source in woody peat. The three components produce a synergistic effect of "acid adjustment-carbon increase-growth promotion".

[0023] 2. Innovative Application Patterns and Ecological Regulation: An innovative spatial and temporal application pattern was proposed, combining "basal application with deep mixing (woody peat + lime + earthworm castings)" with "later surface mulching (straw)." Basal application with deep mixing ensures the amendment acts on the root zone, fundamentally improving the rhizosphere environment. Later, wet mulching with straw on the flooded surface reduces the supply of methanogenic substrates (dissolved organic carbon) for methanogenic bacteria. Furthermore, the decomposition products of straw synergistically inhibit methane formation with the phenolic substances released from the woody peat, achieving a clever combination of soil improvement and greenhouse gas emission reduction.

[0024] 3. Mechanism Integration and Innovation: This approach deeply integrates the "chemical acidification" and "biological carbon enhancement" mechanisms of red soil improvement with the "carbon metabolism regulation" mechanism of paddy field ecology. This solution not only focuses on improving soil chemical properties but also, through the combination and application of specific materials, targets and regulates the microbial community of flooded paddy field soils, particularly inhibiting the activity of methanogenic bacteria—something that traditional single-method improvement techniques cannot achieve. Example

[0025] 1. Experimental Overview: A typical red soil paddy field with consistently low rice yields was selected. Initial soil characteristics: pH 5.0, organic matter content 22.5 g / kg, soil bulk density 1.38 g / cm³, cation exchange capacity (CEC) 12.5 cmol / kg, texture clay loam, and previous crop was fallow. This experiment included 4 treatments, each with 3 replicates, for a total of 12 plots arranged in a randomized block design. Each plot was 30 m² (5m × 6m), and the field ridges were covered with plastic film to prevent water and fertilizer runoff.

[0026] CK (Conventional Fertilization Control): Only local conventional fertilizers (urea, superphosphate, potassium chloride) were applied, and the amount and timing of fertilizer application followed local high-yield practices. Conventional shallow flooding irrigation was maintained.

[0027] T_Lime (single lime application): Based on CK, 10 days before transplanting, according to soil pH and texture (clay loam), apply agricultural lime (quicklime, CaO≥85%) at 100% of the theoretical lime amount to raise the pH to 6.0, i.e., 1237.5 kg / ha.

[0028] T_Peat (single application of woody peat): Based on CK, apply 2.5 tons / hectare of air-dried and pulverized woody peat (particle size ≤5mm) 10 days before transplanting. Do not apply lime.

[0029] T_Invent (the method of this invention, namely 75% of the theoretical lime dosage + peat + organic fertilizer + straw mulch + optimized water management): is carried out in strict accordance with the following specific implementation steps of this invention.

[0030] 2. Specific implementation steps of the present invention: Step 1 (10 days before rice transplanting): After measuring the soil pH, calculate and apply agricultural lime (approximately 75% of the theoretical amount of lime needed to raise the pH to 6.0), and simultaneously apply 2.5 tons / hectare of air-dried woody peat. Use a rotary tiller to shallowly till to a depth of 15 cm; Theoretical lime requirement (kg / hectare) = Soil acidity correction value ΔpH × Soil buffer coefficient × Topsoil weight; In the formula, the "soil acidity correction value" is determined by the difference between the target pH and the current pH; the "soil buffer coefficient" is determined by the CEC or soil texture (e.g., sandy soil, clay). Topsoil weight: calculated based on standard tillage depth (e.g., 20 cm), generally approximately 2,250,000 kg / ha. (To raise the pH of the topsoil of 1 acre by one unit, approximately 33 kg of pure calcium oxide (CaO) needs to be applied; "Soil buffer coefficient": sandy soil (1.0), loam (1.5-2.0), clay loam (2.0-3.0), clay (3.0-4.0).) Taking a clay loam paddy field (measured pH=5.0, target pH=6.0) as an example, the specific amount of lime required can be calculated step by step according to the formula: Theoretical lime requirement = Soil acidity correction value × Soil buffer coefficient × Weight of topsoil. ① Soil acidity correction value: 33 kg / mu / pH × 15 mu / hectare = 495 kg CaO / hectare / pH. The amount of CaO required per kilogram of soil is: 495 kg CaO / hectare / pH ÷ 2,250,000 kg soil / hectare = 2.2 × 10⁻ 4 kg CaO / kg soil / pH unit; ② Soil buffer coefficient: Based on the common correspondence between soil texture and buffer capacity, the typical buffer coefficient range for clay loam is 2.0-3.0.

[0031] In this example, we take the median value, K = 2.5; ③ Topsoil weight: The total soil weight per unit area (hectare) at the standard tillage depth (usually 20 cm) W = 2.25 × 10 6 kg / hectare.

[0032] ④ pH difference: ΔpH = target pH - current pH = 6.0 - 5.0 = 1.0.

[0033] ⑤ Theoretical requirement: (2.20 × 10⁻ 4 (kg / kg / pH) × 2.5 × (2.25 × 10) 6 (kg / ha) = 1237.5 kg CaO / ha ⑥ Actual application rate: theoretical requirement × 75% = 928.13 kg / hectare.

[0034] Step 2 (5 days before rice transplanting): Evenly spread 3.8 tons / hectare of well-rotted earthworm castings on the field surface. Flood the field to a depth of 3-5 cm, then use a water harrow to harrow to a depth of 20 cm to fully mix all the base materials with the mud, and then level the field surface. Step 3 (Rice Transplanting and Field Management): Transplant conventional high-quality indica rice varieties. Within 3 days after transplanting, evenly cover the rows with chopped rice straw from the previous season, with a coverage of approximately 3.0 tons / hectare (dry weight). For water management, during the tillering stage, implement a cycle of "shallow water layer (3cm) - natural drying (no water layer in the field, soil moist) - field drying (field surface cracking)". Maintain a shallow water layer from the booting stage to the heading stage, and alternate between dry and wet conditions in the later stages.

[0035] Step 4 (Topdressing): Apply silicon-zinc fertilizer to the leaves once during the tillering and heading stages.

[0036] Effects of the invention: The method of this invention (T_Invent) exhibits comprehensive and significant synergistic advantages compared to other treatments.

[0037] 1. In terms of soil improvement: its available nutrients (alkaline nitrogen 185 mg / kg, available phosphorus 32.00 mg / kg) and pH value (5.51) were significantly better than those of the control treatments, which reflects the synergistic effect of woody peat and lime in improving fertility and regulating acidity.

[0038] 2. Regarding rice growth and yield: T_Invent optimizes the population structure (number of panicles per unit area 242×10⁻⁶). 4 The highest actual yield (9500 kg / ha) was achieved by combining the grain number per ear (148 grains per ear and a grain filling rate of 89.50%) with the ear traits (148 grains per ear and a grain filling rate of 89.50%), resulting in a significant increase in yield.

[0039] 3. In terms of ecological and environmental effects: T_Invent significantly reduced the cumulative methane emissions (155 kg CH4 / ha) and emission intensity (0.016 g CH4 / kg), while significantly optimizing the soil microbial community, showing the lowest abundance of methanogenic bacteria (1.35 g / kg), while the highest abundance of beneficial bacteria such as methanogenic bacteria, ammonia-oxidizing bacteria, and nitrogen-fixing bacteria.

[0040] The above demonstrates that while increasing production, the present invention effectively promotes soil health and reduces greenhouse gas emissions, achieving multiple goals of green and sustainable agricultural development.

Claims

1. A method for improving the quality and increasing the yield of red soil paddy fields based on woody peat composite improvement, characterized in that, Includes the following steps: Step S1: Base fertilizer application and initial soil mixing: Before rice transplanting, apply agricultural lime and air-dried and crushed woody peat as base fertilizer to the field surface, followed by shallow tillage. Step S2: Deep application of organic fertilizer and harrowing: After shallow plowing, spread the decomposed earthworm castings evenly on the field surface, then irrigate the field and perform deep rotary tillage or water harrowing to ensure that all base materials are fully integrated with the topsoil. Step S3: Straw mulching and water management: After rice transplanting, chopped rice straw is evenly mulched on the field surface between rice rows, and intermittent irrigation is implemented during the rice tillering stage.

2. The method according to claim 1, characterized in that, In step S1, the amount of agricultural lime applied is determined based on the initial pH and texture of the target topsoil. When the soil pH is ≤5.0 and the soil is sandy or loam, the amount of agricultural lime applied is 750-1500 kg / ha; when the soil is clay, the amount of agricultural lime applied is 1500-2250 kg / ha. When the soil pH is 5.0 < ≤5.5 and the soil is sandy or loam, the amount of agricultural lime applied is 750-1125 kg / ha; when the soil is clay, the amount of agricultural lime applied is 1125-1875 kg / ha. When the soil pH is 5.5 < ≤6.0 and the soil is sandy or loam, the amount of agricultural lime applied is 375-750 kg / ha; when the soil is clay, the amount of agricultural lime applied is 750 kg / ha.

3. The method according to claim 1, characterized in that, The amount of woody peat used is 2.0-3.0 tons / hectare, and its particle size is ≤5mm. The depth of shallow tillage is 12-15cm.

4. The method according to claim 1, characterized in that, In step S2, the amount of decomposed earthworm castings used is 3.0-4.5 tons / hectare; the depth of deep rotary tillage or water harrowing is 18-20 cm.

5. The method according to claim 1, characterized in that, In step S3, the amount of rice straw used for mulching is 2.5-3.5 tons / hectare by dry weight, and the chopped length is 10-15cm; the intermittent irrigation mode is a cycle of "shallow water layer - natural drying - field drying".

6. The method according to any one of claims 1 to 5, characterized in that, The method also includes step S4: during the peak tillering and booting stages of rice, apply water-soluble fertilizer containing trace elements such as silicon and zinc to the leaves 1-2 times.

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