A method for reducing greenhouse gas emissions in paddy fields by polyglutamic acid

Abstract

A method for reducing greenhouse gas emissions and increasing rice yields, a treatment model that takes into account economic and ecological benefits. It involves the use method of polyglutamic acid. Dissolve the polyglutamic acid powder in water to prepare a solution with a certain concentration, and then transfer it to an electric sprayer or a shower head and apply it after each fertilization. Prepare it for immediate use, which can achieve the effects of reducing greenhouse gas emissions and increasing rice yields.

Description

Technical Field

[0001] The invention relates to a method for reducing greenhouse gas emissions from rice fields, and in particular to a method for reducing greenhouse gas emissions from rice fields by using a highly efficient microbial fermentation polyglutamic acid product, which is beneficial to reducing greenhouse gas emissions from rice fields and increasing rice production. Background Art

[0002] Polyglutamic acid (PGA) is a high molecular weight anionic polypeptide polymer linked by aminoacyl bonds formed by the polymerization of 500-5000 glutamic acids through α-amino and γ-carboxyl groups, and its molecular weight is usually between 10kDa-10000kDa (Ashiuchi, 2003). Since polyglutamic acid is linked by γ-aminoacyl bonds, there are a large number of carboxyl groups on its molecular chain, which can form a stable bond with molecules containing hydrogen bonds such as water. Therefore, polyglutamic acid molecules have good water solubility, water absorption and water retention (Fu Heng, 2023). Due to the unique function of polyglutamic acid, more and more scholars are using it in fertilizer efficiency. Some studies have found that the application of appropriate concentrations of polyglutamic acid can enhance soil fertility and plant absorption of N, P, and K, and can increase yield (BAI, 2020). Summary of the invention

[0003] A method for applying polyglutamic acid in combination with fertilizer has been invented, which can achieve the effect of reducing greenhouse gas in rice fields and maintaining rice yield. The method is simple to use and easy to promote.

[0004] Weigh 0.25-1kg polyglutamic acid powder and dissolve it in 10L water to prepare 0.25-1kghm -2 Prepare the polyglutamic acid solution as needed, transfer the solution to an electronic sprayer or shower head, and spray it on the stems and leaves of rice after each fertilization.

[0005] The usage amount is small and the method of use is simple. As a highly efficient fertilizer enhancer, it has the characteristics of water solubility and biodegradability, and is non-toxic and harmless to the environment and animals and plants.

[0006] The test site is located in Lanjie Village, Huaqiao Town, Wuxue City (115°30′E, 29°55′N). The area belongs to the rice area in the middle reaches of the Yangtze River, with an altitude of about 20m. It has a subtropical monsoon climate, an average annual temperature of 16.8℃, an average annual rainfall of 1278.7-1442.6mm, muddy fields, and paddy soil. The basic physical and chemical properties of the soil (0-20cm soil layer) at the test site are pH 6.27, bulk density 1.12gcm -3 , organic carbon 22.7gkg -1 , total nitrogen 1.63gkg -1 NH4 + -N50.75mgkg -1 and NO3 --N 2.31 mg / kg -1 。

[0007] Field experiments were conducted in 2021 and 2022, with five different concentrations of polyglutamic acid treatments: control group (1) 0 kg / hm -2 γ-PGA, (2) 0.1 kg / hm -2 γ-PGA, (3) 0.25 kg / hm -2 γ-PGA, (4) 0.5 kg / hm -2 γ-PGA, (5) 1 kg / hm -2 γ-PGA. Each treatment had 3 replicates, and the area of each plot was 40 m 2 (5 m × 8 m). There were ridges between plots and they were covered with black plastic film. Urea (N 46%) was used as nitrogen fertilizer, superphosphate (P2O5 12%) was used as phosphate fertilizer, and potassium chloride (K2O 60%) was used as potassium fertilizer. Among them, 50% of the nitrogen fertilizer (180 kg / hm -2 ) was used as basal fertilizer, 25% as tillering fertilizer, and 25% as panicle fertilizer; all of the phosphate fertilizer (90 kg / hm -2 ) was used as basal fertilizer; 70% of the potassium fertilizer (120 kg / hm -2 ) was used as basal fertilizer and 30% as panicle fertilizer.

[0008] γ-PGA (purity > 99.9%). The amount of polyglutamic acid applied to each plot each time was: (1) 0 g γ-PGA, (2) 0.1 g γ-PGA, (3) 1 g γ-PGA, (4) 2 g γ-PGA, (5) 4 g γ-PGA. Poly-γ-PGA was first dissolved in a large white bottle and then transferred to an electric sprayer or a sprinkler, and evenly applied to the plot before each fertilization. In 2021, the seedlings were raised on May 15, transplanted on the morning of June 21 and the basal fertilizer was applied in the afternoon, the tillering fertilizer was applied on July 4, and the panicle fertilizer was applied on August 19. The paddy field was kept under shallow irrigation, drained and sunned after July 18, and harvested on October 28. In 2022, the seedlings were raised on May 16, sown on June 18, the plots were manually weeded on June 17, transplanted on June 20 and the basal fertilizer was applied in the afternoon, the tillering fertilizer was applied on July 4, and the panicle fertilizer was applied on August 19. Harvested on October 10. The planting density was 25,000 plants per 667 m -2 , 2 plants per hill, the row spacing was 15 cm × 20 cm, and the water depth in each plot was maintained at 5 - 10 cm. The water was drained in time when it rained and the water was replenished in time when there was a water shortage.

[0009] CH4 and N2O emissions from paddy fields were collected and measured by the static dark chamber-gas chromatography method. Before gas sampling, four glass bottles were evacuated and gas samples were collected for 0, 10, 20, and 30 minutes respectively. Sampling was carried out on the 1st, 4th, and 7th days after each fertilization, and then once every 7-10 days. The sampling time was adjusted appropriately according to the local weather; the measurements were carried out within one week after sampling. The measurement was conducted at the Third Comprehensive Building of Huazhong Agricultural University using a Shimadzu GG-14B gas chromatograph. Before rice harvest, a 5m area was marked in the center of each plot. 2 Rice was harvested manually and brought back to the base for threshing. After removing empty grains, the weight was recorded and the moisture content of the rice grains was measured and converted to the weight at a moisture content of 14%.

[0010] In 2021, the cumulative CH4 emissions of the five polyglutamic acid treatment groups were 651.5 kg hm -2 、616.2 kg hm -2 、509.0 kg hm -2 、440.7 kg hm -2 、464.6 kg hm -2 , with a significant reduction ranging from 21.8% to 32.3%; the cumulative N2O emissions of the five polyglutamic acid treatment groups were 4.81 kg hm -2 、4.30 kg hm -2 、3.74 kg hm -2 、3.61 kg hm -2 、3.26 kg hm -2 , with a significant reduction ranging from 22.2% to 32.2%. In 2022, the cumulative CH4 emissions of the five polyglutamic acid treatment groups were 449.4 kg hm -2 、423.8 kg hm -2 、327.2 kg hm -2 、280.6 kg hm -2 、279.9 kg hm -2 , with a reduction ranging from 27.1% to 37.7%; the cumulative N2O emissions of the five polyglutamic acid treatment groups were 6.34 kg hm -2 、5.84 kg hm -2 、5.44 kg hm -2 、5.07 kg hm -2 、4.68 kg hm -2 .

[0011] In 2021, the yields of each treatment were 9521.5 kg hm -2 、9582.4 kg hm -2 、10321.7 kg hm -2, 11073.7 kg / hm -2 , 11451.6 kg / hm -2 , the yields of each treatment in 2022 were 9667.9 kg / hm -2 , 9746.2 kg / hm -2 , 10558.6 kg / hm -2 , 11403.3 kg / hm -2 , 11420.7 kg / hm -2 . Applying polyglutamic acid in 2021 had a significant yield-increasing effect, with a yield increase of 8.4% - 20.2%. Applying polyglutamic acid in 2022 also had a significant yield-increasing effect, with a yield increase of 9.2% - 18.1%. Therefore, applying polyglutamic acid has a significant effect on reducing greenhouse gas emissions and increasing yields.

Claims

1. A method for reducing greenhouse gas emissions in paddy fields, characterized in that: in After fertilizing rice during tillering, green-reverting, and heading stages, a certain amount of polyglutamic acid is formulated into a solution and evenly sprayed on the rice stems and leaves per unit area to achieve the effect of reducing greenhouse gas emissions. The polyglutamic acid solution is prepared by weighing 0.25 - 1 kg of polyglutamic acid powder and dissolving it in water, which is prepared immediately before use. The dosage of polyglutamic acid per hectare is 0.25 - 1 kg, and the greenhouse gases are CH4 and N2O.