METHOD FOR RAPID LOW-COST IMPROVEMENT OF FARMLAND AVAILABLE PHOSPHORUS BY STRAW ROTTING FUNGUS

Abstract

Disclosed is a method for rapid low-cost improvement of farmland available phosphorus by straw rotting fungus, which belongs to the technical field of field returning by straw mushroom planting. The present invention discloses a method for rapid low-cost improvement of farmland available phosphorus by straw rotting fungus. Agricultural waste straw is used as an organic phosphorus fertilizer source and a carbon source, treated and then used as a main raw material for cultivating straw rotting fungus, so as to create suitable environmental conditions such as a carbon-nitrogen ratio and moisture, and provide a good growth environment for the straw rotting fungus. Transformation and release of phosphorus in the straw are rapidly promoted through technical links such as variety selection and sowing of the straw rotting fungus, soil covering and moisture preservation, and management of a mycelium period and a fruiting period, so as to improve an available phosphorus content in soil.

Description

Technical Field The present invention relates to the technical field of field returning by strawmushroom plant- ing, in particular to a . Background Phosphorus is one of essential nutrient elements for plant growth and development. It partic- ipates in synthesis and metabolism processes of various organic substances in plants and plays an important role in maintaining growth and development and enhancing stress resistance. Soil is an important supply source of phosphorus. Supply forms can be divided into organic phospho- rus and inorganic phosphorus, wherein the organic phosphorus mainly comes from animal, plant and microbial residues and metabolites; and the inorganic phosphorus mainlycomes from organic phosphorus mineralization, phosphate dissolution and external phosphorus fertilizer input. In ad- dition, the inorganic phosphorus can be classified into insoluble phosphorus and soluble phos- phorus according to the solubility. The inorganic phosphorus that can be directly absorbed and utilized by plants in soil is called available phosphorus, including orthophosphate (PO43'), meta- phosphate (PO3') and hydrogen phosphate (HPO42'), which is a key index to evaluate soil fertility. The organic phosphorus and the most inorganic phosphorus can only be absorbed by plants after mineralization and decomposition. In a farmland ecosystem, the content of available phosphorus in soil cannot meet needs for normal growth and development of crops, and application of phos- phorus fertilizer has become an important way to improve crop yield and quality. However, a phosphorus utilization rate of crops is generally low, which is often 5%-15%, mainly because phosphate radicals are easily adsorbed and fixed by calcium, iron, aluminium and other ions in the soil, thereby forming insoluble phosphate precipitation. Absorption of a root system becomes difficult, leading to accumulation ofa large amount of phosphorus in the soil; and the accumulation amount increases with increase of cultivation years. Phosphorus accumulation in the soil will not only lead to soil salinization, but will also lead to phosphorus loss, which will seriously affect land productivity and the ecological environment. Therefore, improving availability of phosphorus in farmland soil is of great significance to reduce soil phosphorus accumulation, reduce phosphorus loss and alleviate shortage of phosphorus resources. The content of available phosphorus in soil determines the yield and quality of crops. In order to rapidly improve the availability of soil phosphorus, a large number of scholars in China and abroad have researched and developed a series of technologies. Various manners such as amount reduction and organic material application are adopted to reduce the application amount of chemical phosphorus fertilizer, which are applied in production, such as a straw + deep plough- ing + urea + straw decomposing agent field returning technology, a balanced phosphorus ferti- lizer application technology, an organic-inorganic combined application technology, and a coating phosphorus fertilizer technology. Through application of the above technologies, the application of chemical phosphorus fertilizer has been reduced to some extent, but there are still many short- comings in practical application, as follows: (1) The straw + deep ploughing + urea + straw decomposing agent field returning technol- ogy: release of straw phosphorus is promoted mainly by adjusting a carbon-nitrogen ratio and a microflora structure, thereby reducing application of chemical phosphorus fertilizer. At present, this technology is mainly applied in winter wheat planting. However, it is not widely used in pro- duction. On the one hand, the price of winterwheat is relatively stable, which leads to a low input- output ratio and obvious decline in economic benefits. On the other hand, due to an unstable effect of decomposing agents, slow transformation and decomposition of straw and large resi- dues, the effect of improving soil available phosphorus is not obvious, which causes a series of problems, such as decline of farming quality, increase of pests and diseases, etc. (2) The balanced phosphorus fertilizer application technology: this technology estimates an application amount of phosphorus fertilizer according to a phosphorus demand of crops and an available phosphorus supply of soil, so as to reduce accumulation of soil phosphorus and reduce a risk of environmental pollution. However, under this fertilization technology, phosphate radicals in the fertilizer are easily adsorbed and fixed by calcium, iron, aluminium and other ions in soil, thereby forming insoluble phosphate precipitation, which cannot meet growth needs of crops in middle and late stages. Long-term phosphorus accumulation leads to a risk of soil salinization aggravation and phosphorus loss. (3) The organic-inorganic combined application technology: This technology mainly reduces an application amount of phosphorus fertilizer to certain extent, improves soil quality, and im- proves a soil available phosphorus content and phosphorus availability by using organic fertilizer combined with chemical fertilizer. At present, this technology is mainly applied to economic crops. Although it is also applied to wheat, corn and other crops, the organic fertilizer has a low nutrient content, a large dosage and high input cost, with an additional investment of 9,000 yuan per hectare of farmland. In addition, application of a large number of organic fertilizers will also lead to leaching of phosphorus, nitrogen and heavy metals or the like into the deep soil and pollute groundwater. (4) The coating phosphorus fertilizer technology: This technology is to coat the surface of phosphorus fertilizer particles with a semi-permeable or insoluble film to slow down phosphorus release and improve absorption and utilization of the phosphorus by crops. However, the coating technology is still immature at present; performance of coating materials is unstable with high cost; and the effect of improving soil available phosphorus is not obvious, so it is rarely used in agricultural production. Straw is not only an agricultural by-product, but also a valuable biomass resource. lts total phosphorus content is 0.1%-0.5%. It has the advantages of renewability, a short cycle and a low price. Promoting transformation and utilization of straw phosphorus is conducive to achieving a goal of improving availability of farmland phosphorus. According to statistics, collecting more than 700 million tons of straw every year is equivalent to more than 700,000 tons of phosphorus ferti- lizer. Straw field returning is a mainly popularized technology to improve the availability of soil phosphorus. However, under the condition of rotary tillage throughout the year and straw field returning in successive years, straw decomposition is slow; and the residue is large, which leads to decrease of soil phosphorus availability and even a series of production problems, such as decline of farming quality and increase of pests and diseases. How to realize low-cost, rapid and efficient utilization of straw phosphorus resources has become a breakthrough point to improve effectiveness of farmland phosphorus. Therefore, it is an urgent problem for those skilled in the art to give full play to advantages of straw phosphorus resources and provide a method for rapid low-cost improvement of farmland available phosphorus aiming at problems existing in the existing phosphorus fertilizer application technologies. Summary In view of this, the present invention provides a , which solves problems such as high input cost, low phosphorus availability, soil quality decline in an application process of phosphorus fer- tilizer in the prior art, and relieves a phenomenon of non-point source pollution caused by exces- sive application of the phosphorus fertilizer to some extent. According to the present invention, common crop straw is used as a main raw material to cultivate straw rotting fungus. The advantages of fast growth, strong stress resistance and the like of the straw rotting fungus are utilized to rapidly promote transformation and release of straw phosphorus at low cost, thereby improving an available phosphorus content in soil and promoting absorption and utilization of a crop root system. The present invention not only can promote trans- formation of the phosphorus in straw, but can also rapidly improve the availability of the phospho- rus in soil, and reserve new technologies, new methods and new ways for rapidly improving the quality of cultivated land in a short time. In order to achieve the above purpose, the present invention adopts the following technical solution: A , including the following steps: (1) Straw treatment: collecting crushed corn straw by mechanical bundling; fully mixing and pre-wetting for 3-5 days in proportions of 97.5% for straw, 2.0% for lime and 0.5% for urea; and then transporting the pre-wetted straw to a field for ridging, wherein specifications of a single ridge are 60 cm in width, 20 cm in height and 80 cm in ridge spacing; and the ridge surface is flat for sowing straw rotting fungus; (2) Variety selection and sowing ofthe straw rotting fungus: selecting a variety of straw rotting fungus with wide adaptability; starting sowing when a highest temperature drops to 22-25°C in late autumn and early winter (from middle October to early November), wherein a sowing amount is 300-450 g / mz, with a sowing manner of double-layer staggered hole sowing; for a first layer, sowing on the ridge surface; for a second layer, sowing 5 cm below the ridge surface with a hole spacing of 10 cm; and then covering the pre-wetted straw until the ridge height of 28-30 cm, wherein the ridge surface is high in the middle and low on both sides, with a turtle back shape; (3) Soil covering and moisture preservation of the straw rotting fungus: after sowing, using a ridging machine for soil covering on the ridge immediately, wherein a soil covering material is mainly loam with loose texture, good air permeability, and a soil covering thickness of 2-3 cm; the ridge surface is fully covered; and in order to further improve a moisture preservation effect, a layer of straw can be covered additionally with a thickness of 2-3 cm after the soil covering; (4) Management of a mycelium period of the straw rotting fungus: the mycelium period is from the soil covering to early March in the following year; the management in this period focuses on increasing temperature and controlling moisture; the temperature and moisture can be con- trolled by means of film mulching, micro-spray water replenishing and the like to ensure that the temperature in the ridge is controlled between 10-25°C; and the water content in the ridge is not lower than 40%; (5) Management of a fruiting period of the straw rotting fungus: the fruiting period is from middle March to middle-to-late April; the management in this period focuses on cooling, moisture preservation and water replenishing; the temperature, humidity and moisture can be controlled by sunshade net building and micro-spray irrigation and the like to ensure that the temperature in the ridge is controlled between 1822°C; and the water content in the ridge is not lower than 60%; harvesting is carried outwhen fruiting bodies reach the maturity of 60-70%, with general harvest- ing of 3-4 batches; and water needs to be replenished once after harvesting of each batch of mushroom. Further, the length of the crushed corn straw in step (1) is 3-5 cm. Further, the water content after the pre-wetting in step (1) is more than 70%. Further, the variety of the straw rotting fungus in step (2) is Stropharia rugosa-annulata. According to the technical solution, compared with the prior art, the present invention dis- closes a . Agricultural waste straw is used as an organic phosphorus fertilizer source and a carbon source, treated and then used as a main raw material for cultivating straw rotting fungus, so as to create suitable environmental conditions such as a carbon-nitrogen ratio and moisture, and pro- vide a good growth environment for the straw rotting fungus. Transformation and release of phos- phorus in the straw are rapidly promoted through technical links such as variety selection and sowing of the straw rotting fungus, soil covering and moisture preservation, and management of a mycelium period and a fruiting period, so as to improve an available phosphorus content in soil. The method has the following beneficial effects: (1) The available phosphorus content in soil is significantly increases: through application of the present invention in a farmland, it is found that the available phosphorus content in soil can be increased by 266%-326% compared with a basic value, which is equivalent to providing 66.9- 151.5 kg / hm2 phosphorus fertilizer (P205); and compared with direct straw field returning, the available phosphorus content in soil can be increased by 253%-319%, which is equivalent to providing 66.2-1507 kg / hm2 phosphorus fertilizer (P205). (2) The economic benefit is greatly improved: compared with the direct straw field returning, the application of the present invention can save the cost of phosphorus fertilizer (P205) by 595- 1356 yuan / hmz, increase the crop income by 3913-5294 yuan / hmz, and increase the total eco- nomic benefit by 4589-6650 yuan / hmz, with an increase rate of 343%-530%. (3) The environmental benefit is obviously improved: through the application of this technol- ogy, 956-1301 tons of straw can be consumed per hectare of farmland every year; and the consumption amount is increased by 79.7-108.3 tons compared with that of the direct straw field returning, with an increase rate of 411%-498%. Description of Drawings To more clearly describe the technical solutions in the embodiments of the present invention or in the prior art, the drawings required to be used in the description of the embodiments or the prior art will be simply presented below. Apparently, the drawings in the following description are merely embodiments of the present invention, and for those ordinary skilled in the art, other draw- ings can also be obtained according to the provided drawings without contributing creative labour. Fig. 1 is a process flow chart of the present invention. Detailed Description Technical solutions in the embodiments of the present invention are described clearly and fully below in combination with the drawings in the embodiments of the present invention. Appar- ently, the described embodiments are merely part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embod- iments obtained by those ordinary skilled in the art without contributing creative labour will belong to the protection scope of the present invention. Embodiment 1 A method for rapid low-cost improvement of farmland available phosphorus by Stropharia rugosa-annulata (see Fig. 1 for a process flow chart) includes the following steps: (1) Straw treatment: after corn harvesting in autumn, collecting crushed corn straw (3-5 cm) by mechanical bundling; fully mixing and pre-wetting (water content over 70%) for stacking for 3- 5 days in proportions of 97.5% for straw, 2.0% for lime and 0.5% for urea; and then transporting the pre-wetted straw to a field for ridging, wherein specifications of a single ridge are 60 cm in width, 20 cm in height and 80 cm in ridge spacing; and the whole ridge surface is flat and flattened for sowing Stropharia rugosa-annulata. (2) Variety selection and sowing: selecting Stropharia rugosa-annulata with wide adaptability as a variety of straw rotting fungus, which has the characteristics of strong mycelia, strong stress resistance, a thick stem and a thick cap; starting sowing when a highest temperature drops to 22- 25°C from middle October to early November in the year, wherein a sowing amount is 300-450 g / mz, with a sowing manner of double-layer staggered hole sowing; for a first layer, sowing on the ridge surface; for a second layer, sowing 5 cm below the ridge surface with a hole spacing of 10 cm; and then covering dry straw until the ridge height of 28-30 cm, wherein the ridge surface is high in the middle and low on both sides, with an overall turtle back shape. (3) Soil covering and moisture preservation: after sowing, using a ridging machine for soil covering on the ridge immediately, wherein a soil covering material is mainly loam with loose texture, good air permeability, and a soil covering thickness of 2-3 cm; the ridge surface is fully covered; and in order to further improve a moisture preservation effect, a layer of straw is covered additionally with a thickness of 2-3 cm after the soil covering. (4) Management of a mycelium period: entering a mycelium growth period after the soil cov- ering to early March of the following year; controlling the temperature in the ridge between 10- 25°C; when the material temperature is lower than 10°C, covering the ridge surface with a 0.015 mm ordinary mulching film for mulching thermal insulation, wherein after 60-70 days, the mycelia cover a whole bed; and during the mycelium growth period, when the water content is lower than 40%, replenishing water by micro-spray irrigation to improve the water content in the ridge. (5) Management of a fruiting period: entering a fruiting period from middle March to middle- to-late April; adjusting the temperature, humidity and moisture in a shed and the ridge by sun- shade net building and micro-spray irrigation, wherein when the temperature in the ridge rises to 1822°C with the water content in the ridge reaching 60%-70%, fruiting starts; shading by arch shed sunshade nets during the whole process of fruiting to reduce direct sunlight on the mush- room bodies; when there are a large number of mushroom buds on the ridge surface, entering a harvesting stage; carrying out harvesting when fruiting bodies reach the maturity of 60-70%, with general harvesting of 3-4 batches; and replenishing water once after harvesting of each batch of mushroom. Evaluation of an effect of rapid low-cost improvement of farmland available phosphorus: e harvesting of Stropharia rugosa-annulata, evaluating change characteristics of soil phos- availability, annual economic benefits and annual straw consumption amounts. The re- e shown in Tables 1-4. Table 1 Management Manners of Stropharia Rugoso-annu / aza Straw _ Sowing Soil cov Film Har Har- . SOWIng . . . . . . . tion amount t' amount ering mulching Irrigation Shading vesting vesting ime (t / hmz) (g / mz) (cm) (mm) period times u- Micro- Sun- March October ian, 130.1 18 300 2.0 0.015 spray irri- shade 17-April 4 ina gation net 16 Micro- Sun- March ngqi November _ _ _ 101.1 400 2.6 0.015 spray irri- shade 15-April 4 hina 06 gation net 22 Micro- Sun- March kao, October 126.9 350 2.4 0.015 spray irri- shade 22-April 3 ina 27 gation net 13 Micro- Sun- March zuo, November _ _ _ 95.6 450 3.0 0.015 spray irri- shade 26-April 4 ina 08 gation net 24 Table 2 Effects of Different Straw Utilization Manners on Available Phosphorus Content in Farmland Increase rate __ _ Soil Basic Technical Increase rate _ _ Utilization man- compared With di- Location depth value effect compared with ner rect field returning (cm) (mg / kg) (mg / kg) basic value (%) (° / ) O Direct eld re- 0-20 17.5 1.7 / turning Zhumadian, Field returning 17.2 China by mushroom 0-20 73.3 326.2 319 planting Direct eld re- 0-20 9.1 3.2 / turning Shangqiu, _ Field returning 8.82 China by mushroom 0-20 33.6 281.0 269 planting Direct eld re- 0-20 11 3.8 / turning Lankao, China Field re- 10.6 turning by mush- 0-20 38.8 266.0 253 room planting Direct eld re- _ 0-20 10.4 5.6 / turning Jiaozuo, China Field returning 9.85 by mushroom 0-20 42.7 333.5 311 planting The results in Table 2 show that, compared with the basic value, the available phosphorus content (technical effect) in 0-20 cm soil can be increased by 266%-326%, which is equivalent to providing 66.9-151.5 kg / hm2 phosphorus fertilizer (P205); and compared with direct straw field returning, the available phosphorus content in 0-20 cm soil can be increased by 253%-319%, which is equivalent to providing 66.2-150.7 kg / hm2 phosphorus fertilizer (P205). Table 3 Evaluation of Annual Economic Benefits under Different Straw Utilization Manners Increase Phospho- _ Total compared ln- __ _ Crop rus savmg Crop _ _ _ _ Utlllzatlon _ _ _ benet With direct crease Location rotation Benet benet manner (yuan / eld rate manner (yuan / (yuan / hmz) _ hmz) returning (%) hmz) (yuan / hmz) Direct eld _ Wheat-corn 7.3 1247.4 1254.7 / / returning Zhu- _ _ Field re- _ madian, _ Stropharia _ turning by China rugoso-an- 1363.2 6541.6 7904.8 6650 530 mushroom _ nulatacorn planting Direct eld _ Wheat-corn 1118.6 1125.4 / / returning Shangqiu, Field re- _ _ _ Stropharia China turning by rugoso-an- 602.2 5683.4 6285.5 5160 459 mushroom _ nulatacorn planting Direct eld _ Wheat-corn 9.7 1327.8 1337.5 / / returning Lankao, Field re- _ _ _ Stropharia China turning by rugoso-an- 685.3 5240.9 5926.2 4589 343 mushroom _ nulatacorn planting Direct eld _ Wheat-corn 13.4 1036.3 1049.7 / / returning Jiaozuo, Field re- _ _ _ Stropharia China turning by rugoso-an- 798.3 5062.3 5860.6 4811 458 mushroom _ nulatacorn planting The results in Table 3 show that, by evaluating the economic benefits, it is found that com- pared With direct straw field returning, the cost of phosphorus fertilizer (P205) can be saved by 595-1356 yuan / hmz; the crop Income can be Increased by 3913-5294 yuan / hmz; and the total economic benefit can be increased by 4589-6650 yuan / hmz, With an increase rate of 343%-530%. Table 4 Evaluation ofAnnual Straw Consumption Amounts under Different Straw Utilization Manners Consumption Increased compared Utilization man- Crop rotation Increase Location amount With direct eld return- ner manner _ rate (%) (t / hm2) ing (t / hm2) Direct eld re- Wheat-corn 21.8 / / turning Zhumadian, _ Field returning Stropharia ru- China by mushroom goso-annulata 130.1 108.3 498 planting corn Direct eld re- Wheat-corn 19.8 / / turning Shangqiu, _ Field returning Stropharia ru- China by mushroom goso-annulata 101.1 81.3 411 planting corn Direct eld re- Wheat-corn 23.7 / / turning Lankao, _ Field returning Stropharia ru- China by mushroom goso-annulata 126.9 103.2 435 planting corn Direct eld re- _ Wheat-corn 18.9 / / turning Jiaozuo, _ Field returning Stropharia ru- China by mushroom goso-annulata 95.6 79.7 421 planting corn The results in Table 4 show that, by evaluating straw consumption amounts, it is found that field returning by mushroom planting can consume 95.6-130.1 tons of straw per hectare of farm- land every year, which is 79.7-108.3 tons more than that of direct straw field returning, with an increase rate of411%-498%. The above description ofthe disclosed embodiments enables those skilled in the art to realize or use the present invention. Many modifications made to these embodiments will be apparent to those skilled in the art. General principles defined herein can be realized in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present inven- tion 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 method for rapid and inexpensive improvement of available agricultural land phosphorus by straw rot fungus, which method includes the following steps: (1) Straw treatment: collection of finely ground corn straw by mechanical bundle; mix completely and pre-moisten for 3 - 5 days in a ratio of 97.5% straw, 2.0% lime and 0.5% urea; and then the transport pre-moistened straw to a field to form combs, where the a single comb is 60 cm wide and 20 cm high and the distance between the combs is 80 cm amounts to; (2) Selection of the variety and sowing of straw rot fungus: selecting a variety of straw rot fungus with great adaptability; start sowing when the maximum temperature drops to 22 - 25°C from mid-October to early November, where the sowing rate is 300 - 450 g / m2, with a sowing method of two-layer sowing with staggered holes; the first layer is sown on the ridge; the second a layer of 5 cm below the ridge is sown and the distance between the holes is 10 cm; after which the pre-moistened straw is covered to a comb height of 28 - 30 cm, where the comb is high in the middle and low on both sides, in the shape of the back of a turtle; (3) Ground cover and moisture retention of the straw rot fungus: after sowing immediate application of a ridging machine for ground cover on the ridge, where the ground cover is 2 - 3 cm thick and the comb surface is completely covered; and after the ground cover, apply another layer of straw with a thickness of 2 - 3 cm; (4) management of a mycelium period of the straw rot fungus; management in the mycelium period that runs until early March of the following year, during which management is aimed at increasing the temperature and regulating humidity to ensure that the temperature in the comb is kept between 10 - 25°C and the water content in the comb is not less than 40%; (5) management of the straw rot fungus fruiting period: management during the fruiting period that runs from mid-March to mid-late April, with management focused on cooling, moisture retention and water replenishment to ensure the temperature in the comb is kept between 18 - 22°C and the water content in the comb is not lower than 60%; harvested when the fruiting bodies reach a maturity level of 60 - have reached 70%, generally harvested in 3 to 4 batches; after the harvest each batch of mushrooms once water is replenished.

2. The method for rapid and inexpensive improvement of phosphorus available on agricultural land by straw rot fungus according to claim 1, wherein the length of the crushed corn straw in step (1) 3 - 5 cm is.

3. The method for rapid and inexpensive improvement of phosphorus available on agricultural land by straw rot fungus according to claim 1, wherein the water content after pre-wetting in step (1) exceeds 70%.

4. The method for rapid and inexpensive improvement of agricultural land available phosphorus by straw rot fungus according to claim 1, wherein the variety of the straw rot fungus in step (2) is Stropharia rugosa-annulata. Fig. 1

Images