Fertilizer for increasing soil fertility of cassava field and fertilizing method

Abstract

The invention discloses a fertilizer for increasing soil fertility of a cassava field. The fertilizer is prepared by applying 1 / 2 nitrogen-phosphorus-potassium compound fertilizer to cassava carbon soil; the fertilizing amount of the nitrogen-phosphorus-potassium compound fertilizer is the optimal dosage, and the cassava carbon soil is surface soil of a cassava planting zone after the cassava in season is harvested and smoldering products of waste cassava stems and leaves and old seed stems. The invention further discloses a fertilizing method for increasing the soil fertility of the cassava field. The fertilizing method comprises the following steps: preparing the nitrogen-phosphorus-potassium compound fertilizer; preparing cassava carbon soil; 1 / 2 of chemical fertilizer is reduced on the basis of recommended nitrogen-phosphorus-potassium fertilizer application, and the cassava carbon soil is applied in a matched mode; the cassava carbon soil is spread in a planting area before cassava planting, and the nitrogen-phosphorus-potassium compound fertilizer is applied in holes at a time 45-60 days after cassava planting. The method is beneficial to the recovery and improvement of soil nutrients and biological fertility, the richness and diversity of rhizosphere soil bacteria and fungi are obviously increased, the microbial community structure is obviously improved, the abundance of carbon and nitrogen metabolism functional genes is obviously improved, the investment of chemical fertilizers is reduced, and the yield loss caused by continuous cropping of cassava is effectively eliminated.

Description

Technical Field

[0001] The invention relates to the technical field of soil fertility, and in particular to a fertilizer for increasing soil fertility in a cassava field and a fertilization method for increasing soil fertility in a cassava field. Background Art

[0002] Soil fertility refers to the ability of soil to supply and regulate the water, nutrients, heat, air and other living conditions required for plant growth during the life of plants. Soil fertility can be divided into natural fertility and artificial fertility according to the cause. The former refers to the fertility formed under the influence of the five major soil-forming factors (climate, biology, parent material, topography and age), which mainly exists in uncultivated natural soil; the latter refers to the fertility manifested under the influence of long-term artificial cultivation, fertilization, irrigation and other various agricultural activities, which mainly exists in cultivated (farmland) soil. Combining land use with land conservation and preventing fertility decline with soil management are the basic principles for maintaining and improving soil fertility levels. Specific measures include: increasing the application of organic fertilizers, planting green manures, returning straw to the field and rationally applying chemical fertilizers, so as to not only facilitate the high yield of crops in the current season, but also facilitate the recovery and improvement of soil fertility.

[0003] Cassava Manihotes culenta Crantz) is a tropical crop of the Euphorbiaceae family, cassava. As one of the three major tuber crops in the world, it is the staple food of more than 1 billion people in Africa, Asia and America. Its tubers are important raw materials for starch processing and alcohol production. my country is heavily dependent on imports of cassava, so the development of cassava production is of great significance. The high yield of cassava is inseparable from the input of fertilizers, but the long-term unreasonable application of fertilizers (no fertilizer, partial fertilizer application, excessive fertilizer application, etc.) causes the decline of soil biological fertility, which is manifested in the serious impact on microbial communities and diversity, soil nutrients, etc., resulting in limited cassava production. In addition, due to the long-term continuous cropping of cassava, the continuous cropping obstacles caused by pathogens infecting the roots of plants, which in turn affects the high yield of cassava. For this reason, in cassava planting areas, it is necessary to scientifically adjust the fertilizer application strategy and formulate reasonable fertilization methods to provide a basis for the sustainable development of agricultural production and sustainable land use. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes the following technical solutions: A fertilizer for increasing the fertility of cassava soil, comprising: cassava carbon soil combined with 1 / 2 nitrogen, phosphorus and potassium compound fertilizer, Cassava carbon soil is the product of burning the surface soil of the cassava planting belt after the cassava is harvested in the current season, as well as the discarded cassava stems and leaves and old seed stems. The application rate is 30-45 t / hm 2 .

[0005] The mass percentage of 1 / 2 nitrogen, phosphorus and potassium compound fertilizer to cassava carbon soil is 0.24:100~0.50:100.

[0006] According to the embodiment of the present invention, the application amount of 1 / 2 nitrogen, phosphorus and potassium compound fertilizer is N 40~60 kg / hm 2 、P2O5 20~30kg / hm 2 、K2O 45~60 kg / hm 2 .

[0007] According to an embodiment of the present invention, the basic soil physicochemical properties of cassava fields are: High fertility test area: pH 5.35, organic matter 10.30 g / kg, total nitrogen 0.54 g / kg, available phosphorus 34.1 mg / kg, and available potassium 45.2 mg / kg; Medium fertility test area: pH 5.13, organic matter 8.40 g / kg, total nitrogen 0.35 g / kg, available phosphorus 24.6 mg / kg, and available potassium 36.9 mg / kg; Low fertility test area: pH 5.24, organic matter 6.40 g / kg, total nitrogen 0.28 g / kg, available phosphorus 13.7 mg / kg, and available potassium 29.0 mg / kg.

[0008] A fertilization method for increasing soil fertility in cassava fields, comprising: preparing cassava carbon soil; Equipped with nitrogen, phosphorus and potassium compound fertilizer; Based on the recommended nitrogen, phosphorus and potassium fertilizers, reduce the application of chemical fertilizers by 1 / 2 and apply cassava carbon soil, that is, replace 1 / 2 of the chemical fertilizers with homemade cassava carbon soil; Cassava carbon soil should be evenly spread in the planting area before planting cassava, and nitrogen, phosphorus and potassium compound fertilizer should be reduced by 1 / 2 and applied once in holes 45 to 60 days after planting cassava.

[0009] According to an embodiment of the present invention, the cassava carbon soil production method is to collect the discarded stems and leaves and old seed stems after cassava harvest in the nearby cassava planting area, spread them into haystacks, shovel out the surface soil of the planting area and evenly spread it on the haystacks, and burn the haystacks from the outside to the inside under dry conditions to obtain a stoking product.

[0010] According to an embodiment of the present invention, cassava carbon soil is evenly spread in the planting area before cassava is planted, and nitrogen, phosphorus and potassium compound fertilizer is applied once in holes 45 to 60 days after cassava is planted.

[0011] According to an embodiment of the present invention, cassava carbon soil is prepared by laying discarded cassava stems and old seed stems under the topsoil and then simmering them for 7 to 10 days, then digging up the burned soil pile, cooling it, stirring and mixing it, and evenly returning it to the cassava planting area after sieving.

[0012] According to an embodiment of the present invention, the haystack is a nearly circular haystack with a height of 1.4-2.0 m and a diameter of about 2 m. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 , Figure 4 , Figure 7 This is a schematic diagram of fresh potato yield under different fertilization treatments.

[0014] Figure 2 , Figure 5 , Figure 8 is the alpha diversity index of bacteria and fungi under different fertilization treatments.

[0015] Figure 3 , Figure 6 , Fig. 9 Functional predictions of bacteria (a) and fungi (b) under different fertilization treatments based on FAPROTAX and FUNGuild.

[0016] In the figure, CK means no fertilizer; NPK means the recommended amount of nitrogen, phosphorus and potassium compound fertilizer; 1 / 2NPK+FYM means the nitrogen, phosphorus and potassium fertilizer is reduced by 1 / 2 and cassava carbon soil is applied. DETAILED DESCRIPTION

[0017] The following is a description of the exemplary embodiments of the present application, including various details of the embodiments of the present application to facilitate understanding, which should be considered as merely exemplary. Therefore, it should be recognized by those of ordinary skill in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. Similarly, for clarity and conciseness, the description of well-known functions and structures is omitted in the following description.

[0018] The technical solution of the present invention is described in detail below.

[0019] The inventor has established a long-term positioning test observation point for more than 30 years to carry out fertilizer efficiency comparison experiments, mainly setting up no fertilization, full application of chemical fertilizers, and 1 / 2 reduction of chemical fertilizers + cassava carbon soil treatment. The yield and starch content of the treatment with 1 / 2 reduction of chemical fertilizers + cassava carbon soil can reach the level of full chemical fertilizers, and are significantly higher than the treatment without fertilization. The soil pH, organic matter, total nitrogen, total phosphorus, available phosphorus and available potassium content are all significantly higher than the treatment with full application of chemical fertilizers. The diversity of soil bacteria and fungi in the treatment with 1 / 2 reduction of chemical fertilizers + cassava carbon soil is significantly improved, and the structure of microbial communities is significantly improved. The abundance of carbon and nitrogen metabolism functional genes is significantly increased, and the soil chemical properties and biological fertility are significantly improved.

[0020] The fertilizer for increasing the fertility of cassava soil comprises: 1 / 2 of the recommended amount of nitrogen, phosphorus and potassium compound fertilizer and cassava carbon soil. The nitrogen, phosphorus and potassium compound fertilizer is mainly composed of urea, calcium magnesium phosphate fertilizer and potassium chloride. The fertilizer application amount of the full amount of chemical fertilizer is N 90-120 kg / hm 2、P2O5 40~60 kg / hm 2 、K2O 90~120 kg / hm 2 .

[0021] Cassava carbon soil is a kind of planting material, which is not the same as burnt soil, but the principles of the two are similar. They are clay that has been fired at high temperature and is in granular form. The main functions of using it for plant cultivation are ventilation, moisture retention, water retention, root strengthening, and germination. It also contains a variety of trace elements needed by plants and can promote plant nutrient absorption. Cassava carbon soil has the following characteristics under acidic or alkaline conditions: the surface humus content is extremely high, the humification effect is obvious, and the soil bulk density can be as small as about 0.7. The cassava carbon soil of the present invention is the simmered product of the surface soil of the planting belt after the harvest of cassava in the current season and the discarded cassava stems and leaves and old seed stems; that is, after the previous crop of cassava tubers are harvested, the discarded stems and leaves, old seed stems and other by-products are piled up in the field to dry naturally, a corner with higher terrain is selected, the collected discarded by-products are piled up to a height of about 30 cm and a diameter of about 2 m, the surface soil of the cassava test field is shoveled up and evenly spread on the discarded by-products with a thickness of about 5 cm, and the discarded by-products and surface soil are piled up again in this way, and 4 to 6 layers can be repeatedly piled up, ignited from all sides, and burned from the outside to the inside, and after simmering for 7 to 10 days, the burned soil pile is naturally cooled, fully mixed, sieved, and stored in bags, and evenly spread in the planting area before planting cassava in the next season, holes are made, cassava seed stems are planted, and nitrogen, phosphorus and potassium fertilizers are applied to the holes once 45 to 60 days after the cassava is planted. That is, cassava carbon soil is the simmering product of the surface soil of the cassava planting zone after the cassava is harvested in that season and the discarded cassava stems and leaves and old seed stems.

[0022] The mass ratio of nitrogen, phosphorus and potassium compound fertilizer to cassava carbon soil is 0.24:100 ~0.50:100. This ratio is determined according to the actual growth conditions of the cassava field.

[0023] According to an embodiment of the present invention, the amount of nitrogen, phosphorus and potassium fertilizer applied is N 100 kg / hm 2 、P2O5 50 kg / hm 2 、K2O 100kg / hm 2 .

[0024] It should be noted that the long-term positioning experiment was carried out at the cassava experimental base of the Institute of Tropical Crop Variety Resources of the Chinese Academy of Tropical Agricultural Sciences (ICR) in Baodao New Village, Danzhou City, Hainan Province in 1992. The three-year experimental materials from 2020 to 2022 were selected as the content of this study on the experimental timeline. The soil in the experimental site is brick red soil developed from granite. The basic physical and chemical properties of the initial soil in the 1992 experiment were: pH 5.35, organic matter 8.40 g / kg, total nitrogen 0.25 g / kg, available phosphorus 24.6 mg / kg, and available potassium 36.9 mg / kg.

[0025] The fertilization method for increasing the fertility of cassava soil comprises: preparing the cassava carbon soil; preparing the nitrogen, phosphorus and potassium compound fertilizer with the above-mentioned component ratio; reducing the application of 1 / 2 chemical fertilizers on the basis of the recommended nitrogen, phosphorus and potassium fertilization and applying the cassava carbon soil, that is, replacing 1 / 2 chemical fertilizers with the self-made cassava carbon soil; the cassava carbon soil is evenly spread in the planting area before cassava planting, and the nitrogen, phosphorus and potassium compound fertilizer is applied once in holes 45 to 60 days after cassava planting.

[0026] According to an embodiment of the present invention, the cassava carbon soil production method is to collect discarded cassava stems and old seed stems from nearby cassava planting areas, lay them into haystacks, shovel out the surface soil and evenly lay it on the haystacks, and simmer the haystacks from the outside to the inside under dry conditions. The specific production process is as follows:

[0027] The collected discarded cassava leaves and seed stems are piled into haystacks and mixed with the surface soil of the cassava field, and the haystacks are ignited and smoldered. After the discarded cassava leaves, seed stems and surface soil are completely smoldered, they are cooled and set aside.

[0028] After burning the cassava carbon soil, let it cool before use. Because the freshly burned cassava carbon soil is very alkaline, if it is point-point fertilization, the carbon soil and the hole soil should be fully mixed before planting the seed stems. If it is planted in the hole, the carbon soil should be applied away from the seed stems, and it is forbidden to cover the seed stems thickly, otherwise the alkaline water released after the carbon soil absorbs water will burn the seed buds.

[0029] According to an embodiment of the present invention, cassava carbon soil is evenly spread on the planting area before cassava is planted, and nitrogen, phosphorus and potassium compound fertilizer is reduced by 1 / 2 and applied once in holes 45 to 60 days after cassava is planted.

[0030] According to an embodiment of the present invention, the cassava carbon soil is prepared by laying discarded cassava stems and old seed stems under the surface soil and then simmering them for 7 to 10 days, then digging up the burned soil pile, cooling it, fully stirring it and evenly returning it to the cassava planting area.

[0031] According to an embodiment of the present invention, the haystack is a nearly circular haystack with a height of 1.4-2.0 m and a diameter of about 2 m.

[0032] The following will compare the fresh tuber yield, α diversity index and predicted functional relative abundance of cassava cultivated with fertilizers of different composition ratios with those cultivated without nitrogen, phosphorus and potassium fertilizers and with the recommended nitrogen, phosphorus and potassium dosages.

[0033] (I) The method and steps for measuring the fresh cassava yield include: Yield measurements were carried out during the cassava harvest period of the long-term positioning experiment in 2020, 2021 and 2022, and soil samples were collected and the soil physical and chemical properties and microbial community were determined.

[0034] (1) Determination of theoretical yield Theoretical yield (kg / mu) =

[0035] The effective number of plants per mu is converted by the number of plants in the plot, the number of tubers per plant is converted by the average value of 10 plants, and the weight of a single potato is converted by dividing the weight of 10 tubers by the number of 10 tubers.

[0036] (2) Measured yield: In each plot, remove the side rows and calculate the yield of all remaining tubers and convert it into per-mu yield.

[0037] (II) Tests on soil physical and chemical properties are conducted in accordance with national standards.

[0038] 3. Determination of soil microbial community High-throughput sequencing technology was used to analyze the diversity of soil bacteria and fungi, and FAPROTAX and FUNGuild were used to predict the functions of bacteria and fungi, respectively.

[0039] 1. The soil alpha diversity index is used to analyze the diversity of microbial communities in samples. The diversity analysis (alpha diversity) of a single sample can reflect the richness and diversity of the microbial community in the sample, including a series of statistical analysis indices, species diversity curves and species cumulative box plots to evaluate the differences in species richness and diversity of microbial communities in each sample. Alpha diversity focuses on the number of species in a local uniform habitat, so it is also called diversity within the habitat. In the analysis, several different alpha diversity indices, including observed-species, Chao1, Shannon, Simpson, and Good-coverage, are mainly selected to characterize the diversity and uniformity of species distribution in the sample, and to intuitively display the sequencing depth and data volume. The Chao1 index and Shannon index are widely used alpha diversity measurement indices in ecology: the Chao1 index is used to estimate the total number of species contained in the community sample. At the same time, because the species information with abundances of 1 and 2 is added to its calculation, it can well reflect the existence of low-abundance species in the community. Shannon Index: Also called Shannon-Wiener Index, its calculation takes into account the total number of categories in the sample (Richness) and the proportion of each category (Abundance). The higher the diversity of the community and the more evenly the species are distributed, the larger the Shannon Index.

[0040] 2. Function prediction of bacteria and fungi. FAPROTAX is more suitable for functional annotation prediction of biogeochemical cycles of environmental samples (especially the cycles of carbon, hydrogen, nitrogen, phosphorus, sulfur and other elements). Because it is based on published and verified literature on culturable bacteria, its prediction accuracy is good. FAPROTAX is more flexible and predicts ecological functions by identifying the genus and species of bacteria. Based on currently published literature or authoritative website data, FUNGuild first divides fungi into three categories according to their nutritional methods: pathotrophs - obtain nutrition by damaging host cells (including phagotrophs); symbiotrophs - obtain nutrition by exchanging resources with host cells; saprotrophs - obtain nutrition by degrading dead host cells. Based on the three major nutritional modes, it is further subdivided into several guilds: animal pathogens, arbuscular mycorrhizal fungi, ectomycorrhizal fungi, ericoid mycorrhizal fungi, foliar endophytes, lichenicolous fungi, lichenized fungi, mycoparasites, plant pathogens, undefined root endophytes, undefined saprotrophs and wood saprotrophs; it also includes three types of fungi with special morphology: yeast, faculty yeast and thallus. By linking the fungal species classification with the functional guild classification through bioinformatics methods, fungi can be functionally classified.

[0041] The specific embodiments of the fertilizer and fertilization method for increasing soil fertility of cassava fields of the present invention are described in detail below.

[0042] Table 1 Data on fertilizers and fertilization methods for increasing soil fertility in cassava fields

[0043] Example 1 Example 1 is the test result after 29 years of continuous fertilization. The fresh cassava yields of each treatment in Example 1 are compared, and the results are shown in Figure 1The fresh potato yields of NPK treatment and 1 / 2NPK+FYM treatment were significantly higher than those of CK treatment, with increases of 120.3% and 122.6%, respectively. Compared with NPK treatment, 1 / 2NPK+FYM treatment showed a trend of increasing yield, but there was no significant difference between the two. This shows that reducing the application of chemical fertilizers and applying carbon soil can obtain higher fresh potato yields, while also reducing the application of chemical fertilizers and reducing production costs.

[0044] The physical and chemical properties of the soil of the cassava fields treated in Example 1 were compared, and the results are shown in Table 2.

[0045] Table 2 shows that compared with CK and NPK treatments, 1 / 2NPK+FYM has a significant overall improvement effect on soil fertility, significantly increasing soil pH, total nitrogen (TN), total phosphorus (TP), available phosphorus (AP) and available potassium (AK) content. Compared with NPK treatment, the pH, TN, TP, AP and AK of 1 / 2NPK+FYM increased by 16.7%, 20.9%, 63.6%, 131.4% and 65.3%, respectively. Overall, compared with NPK treatment, the overall soil fertility of the reduced fertilizer application and carbon soil application increased by 46.0%, with a significant improvement effect.

[0046] Table 2 Comparison of physical and chemical properties of soils treated differently in Example 1

[0047] The α diversity index of soil microorganisms in each cassava field treated in Example 1 was compared, and the results are shown in Figure 2 .Depend on Figure 2 It can be seen that compared with CK, the 1 / 2NPK+FYM treatment significantly increased the Chao1 index of bacterial and fungal community richness, and at the same time increased the Shannon value of bacterial diversity index; compared with full NPK fertilization, 1 / 2NPK+FYM had no significant effect on the Chao1 index of bacteria and fungi, but significantly increased the Shannon value of bacterial diversity index.

[0048] The relative abundance of soil microbial functions in each cassava field treated in Example 1 was compared, and the results are shown in Figure 3 .Depend on Figure 3 It can be seen that compared with the CK and NPK treatments, the 1 / 2NPK+FYM treatment significantly increased the abundance of functional genes in bacterial and fungal communities, significantly increased the relative abundance of nitrifying bacteria, aerobic ammonia oxidizing bacteria and chemoheterotrophic bacteria, and significantly increased the relative abundance of saprophytes. Example 2

[0049] Example 2 is the test result after continuous fertilization for 30 years. The fresh cassava yields of each treatment in Example 2 are compared, and the results are shown in Figure 4The fresh potato yields of NPK and 1 / 2NPK+FYM treatments were significantly higher than those of CK treatment, with increases of 191.2% and 134.7% respectively; there was no significant difference in fresh potato yields between NPK and 1 / 2NPK+FYM treatments. This shows that reducing the use of chemical fertilizers and applying carbon soil can reduce the use of chemical fertilizers and production costs without reducing production.

[0050] The physical and chemical properties of the soil of the cassava fields treated in Example 2 were compared, and the results are shown in Table 3.

[0051] Table 3 shows that compared with CK and NPK treatments, 1 / 2NPK+FYM has a significant overall improvement effect on soil fertility, which significantly increases soil pH, organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), available phosphorus (AP) and available potassium (AK) content. Compared with NPK treatment, the pH, SOC, TN, TP, AP and AK of 1 / 2NPK+FYM increased by 23.2%, 58.1%, 39.6%, 63.6%, 256.8% and 174.5%, respectively. Overall, compared with NPK treatment, the overall soil fertility of the soil with reduced fertilizer application and carbon application increased by 88.8%, with a significant improvement effect.

[0052] Table 3 Comparison of physical and chemical properties of soils treated differently in Example 2

[0053] The α diversity index of soil microorganisms in each cassava field treated in Example 2 was compared, and the results are shown in Figure 5 .Depend on Figure 5 It can be seen that compared with CK, the 1 / 2NPK+FYM treatment significantly increased the Chao1 index of bacterial and fungal community richness and the Shannon value of bacterial diversity index; there was no significant difference between the full NPK fertilization and the 1 / 2NPK+FYM treatment.

[0054] The relative abundance of soil microbial functions in each cassava field treated in Example 2 was compared, and the results are shown in Figure 6 .Depend on Figure 6 It can be seen that compared with the CK and NPK treatments, the 1 / 2NPK+FYM treatment significantly increased the abundance of functional genes in bacterial and fungal communities, significantly increased the relative abundance of nitrifying bacteria, aerobic ammonia oxidizing bacteria and chemoheterotrophic bacteria, and significantly increased the relative abundance of saprophytes. Example 3

[0055] Example 3 is the test result after continuous fertilization for 31 years. The fresh cassava yields of each treatment in Example 3 are compared, and the results are shown in Figure 7The fresh potato yield of NPK treatment and 1 / 2NPK+FYM treatment was significantly higher than that of CK treatment, with increases of 104.0% and 131.2%, respectively. Compared with NPK treatment, 1 / 2NPK+FYM treatment showed a trend of increasing yield, but there was no significant difference.

[0056] The physical and chemical properties of the soil of the cassava fields treated in Example 3 were compared, and the results are shown in Table 4.

[0057] Table 4 shows that compared with CK and NPK treatments, 1 / 2NPK+FYM significantly improved soil fertility, significantly increasing soil pH, organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), available phosphorus (AP) and available potassium (AK) content. Compared with NPK treatment, the pH, SOC, TN, TP, AP and AK of 1 / 2NPK+FYM increased by 13.6%, 24.5%, 43.1%, 26.3%, 213.2% and 62.8%, respectively. Overall, compared with NPK treatment, the overall soil fertility of the soil with reduced fertilizer and carbon application increased by 54.7%, with a significant improvement effect.

[0058] Table 4 Comparison of physical and chemical properties of soils treated differently in Example 3

[0059] The α diversity index of soil microorganisms in each cassava field treated in Example 3 was compared, and the results are shown in Figure 8 .Depend on Figure 8 It can be seen that compared with CK, the 1 / 2NPK+FYM treatment significantly increased the Chao1 index of bacterial and fungal community richness and the Shannon value of bacterial diversity index; compared with full NPK fertilization, 1 / 2NPK+FYM had no significant effect on the Chao1 index of bacteria and fungi; but significantly increased the Shannon value of bacterial diversity index.

[0060] The relative abundance of soil microorganisms in each cassava field treated in Example 3 was compared, and the results are shown in Fig. 9 .Depend on Fig. 9 It can be seen that compared with the CK and NPK treatments, the 1 / 2NPK+FYM treatment significantly increased the abundance of functional genes in bacterial and fungal communities, significantly increased the relative abundance of nitrifying bacteria, aerobic ammonia oxidizing bacteria and chemoheterotrophic bacteria, and significantly increased the relative abundance of saprophytes.

[0061] Although the above results describe the embodiments of the present application, the present application is not limited to the above specific embodiments and application fields, and the above specific embodiments are merely illustrative and instructive, rather than restrictive. A person of ordinary skill in the art can make many forms under the guidance of this specification and without departing from the scope of protection of the claims of the present application, all of which belong to the protection of the present application.

Claims

1. A fertilizer for increasing soil fertility in cassava fields, comprising: Cassava carbon soil is combined with 1 / 2 nitrogen, phosphorus and potassium compound fertilizer. The cassava carbon soil is the simmered product of the surface soil of the cassava planting belt after the cassava is harvested in the current season and the discarded cassava stems and leaves and old seed stems. The dosage is 30-45 t / hm 2 , The application ratio of the 1 / 2 nitrogen, phosphorus and potassium compound fertilizer to the cassava carbon soil is 0.24:100~0.50:

100.

2. The fertilizer for increasing soil fertility of cassava fields according to claim 1, wherein the recommended fertilization rate of the nitrogen, phosphorus and potassium compound fertilizer is N 90-120 kg / hm 2 、P2O5 40~60 kg / hm 2 、K2O 90~120 kg / hm 2 .

3. The fertilizer for increasing soil fertility of cassava fields according to claim 1, wherein the fertilization rate of the 1 / 2 nitrogen, phosphorus and potassium compound fertilizer is N 45-60 kg / hm 2 、P2O5 20~30 kg / hm 2 、K2O 45~60 kg / hm 2 .

4. The fertilizer for increasing soil fertility of cassava fields according to claim 1, wherein the basic soil physical and chemical properties of the cassava fields are as follows: High fertility test area: pH 5.35, organic matter 10.30 g / kg, total nitrogen 0.54 g / kg, available phosphorus 34.1 mg / kg, and available potassium 45.2 mg / kg; Medium fertility test area: pH 5.13, organic matter 8.40 g / kg, total nitrogen 0.35 g / kg, available phosphorus 24.6 mg / kg, and available potassium 36.9 mg / kg; Low fertility test area: pH 5.24, organic matter 6.40 g / kg, total nitrogen 0.28 g / kg, available phosphorus 13.7 mg / kg, and available potassium 29.0 mg / kg.

5. A method for increasing soil fertility in a cassava field, comprising: Equipped with 1 / 2 nitrogen, phosphorus and potassium compound fertilizer according to claim 1; Prepare the cassava carbon soil according to claim 1; Based on the recommended nitrogen, phosphorus and potassium fertilizers, 1 / 2 of the chemical fertilizers are reduced and the cassava carbon soil is applied, that is, 1 / 2 of the chemical fertilizers are replaced with the homemade cassava carbon soil; The cassava carbon soil is evenly spread in the planting area before planting cassava, and the 1 / 2 nitrogen, phosphorus and potassium compound fertilizer is applied once in holes 45 to 60 days after planting cassava.

6. The fertilization method for increasing soil fertility in cassava fields according to claim 5, wherein the cassava carbon soil making method is to collect discarded stems and leaves and old seed stems after cassava harvest in a cassava planting area nearby, lay them into haystacks, shovel out the topsoil in the planting area and evenly lay it on the haystacks, and burn the haystacks from the outside to the inside to obtain a smoldering product under dry conditions.

7. The fertilizing method for increasing soil fertility in cassava fields according to claim 5, wherein cassava carbon soil is broadcasted in the planting area before cassava planting, and 1 / 2 nitrogen, phosphorus and potassium compound fertilizer is applied in a one-time hole application 45 to 60 days after cassava planting.

8. The fertilization method for increasing soil fertility in cassava fields according to claim 6, wherein the cassava carbon soil is prepared by laying discarded cassava stems and leaves and old seed stems on the lower layer of the topsoil and then stewing them for 7 to 10 days, then the burned soil pile is dug up, cooled, stirred and mixed, and evenly returned to the cassava planting area after sieving.

9. The method for applying fertilizer to increase soil fertility in cassava fields according to claim 5, wherein the haystack is a nearly circular haystack with a height of 1.4 to 2.0 m and a diameter of about 2 m.

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