CN107889705B

CN107889705B - Combined cadmium reduction method for rice basal application passivant viability reduction and additional iron fertilizer root control in tillering stage

Info

Publication number: CN107889705B
Application number: CN201711183859.0A
Authority: CN
Inventors: 王兴祥; 黄高翔; 丁昌峰; 周志高; 李孝刚; 徐昌旭
Original assignee: Institute of Soil Science of CAS
Current assignee: Institute of Soil Science of CAS
Priority date: 2017-11-23
Filing date: 2017-11-23
Publication date: 2020-11-03
Anticipated expiration: 2037-11-23
Also published as: CN107889705A

Abstract

The invention provides a combined cadmium reduction method for rice basal application passivant viability reduction and additional application iron fertilizer root control in a tillering stage. The method comprises the steps of applying 100-300 kg/mu of alkaline passivation materials such as lime and the like to a base before planting the rice; in the early stage of tillering of rice, the semi-moist state of soil is kept, 7.5 kg/mu of iron fertilizer is uniformly applied to the soil, and the soil is flooded to the rice milk stage or later after being applied for 2 days. The method integrates the functions of applying a passivator to reduce the activity of cadmium in soil and applying an iron fertilizer to enhance the cadmium resistance of the iron film on the surface of the rice root. For acid soil with medium and light cadmium exceeding the standard, compared with the control, the lime base application alone, the iron fertilizer dressing alone and the lime and iron fertilizer mixed base application treatment, the cadmium concentration of the brown rice of the rice is respectively reduced by 74.6-75.4%, 52.6-57.1%, 66.7-69.4% and 45.5-51.6% by the combined reduction and segregation method.

Description

Combined cadmium reduction method for rice basal application passivant viability reduction and additional iron fertilizer root control in tillering stage

Technical Field

The invention relates to the technical field of safe production of farmland with medium and light pollution, in particular to a safe production technology of paddy rice in farmland with medium and light cadmium pollution. In particular to a combined cadmium reduction method for rice basal application passivant viability reduction and topdressing iron fertilizer root control in a tillering stage.

Background

Cadmium pollution in farmland directly threatens the quality safety of agricultural products in China and the sustainable development of agriculture, such as cadmium rice events in places such as Guangdong Hunan and the like. Aiming at the characteristics of low cadmium pollution degree and large area of farmland in China, farmland agriculture and the like, the research and development of a farmland safe utilization technology which is efficient, economical, rapid, simple, convenient, reproducible and easy to popularize is urgently needed. At present, a lot of researches on cadmium-polluted soil treatment and safe utilization are carried out, including cadmium low-accumulation variety breeding, passivant development and application, planting system adjustment, agricultural technology and the like. The cadmium low accumulation variety is difficult to consider both yield and quality, and the actual large-area popularization and application are rare; the passivator is developed more, mainly comprises lime, organic fertilizer, biochar, sepiolite, hydroxyapatite and the like, and can reduce the absorption of rice to cadmium to a certain degree by mainly increasing the pH of soil, changing the form of cadmium and reducing the effective cadmium content in the soil. However, under the condition of increasing pH by applying an alkaline passivator, the formation of an iron film on the surface of rice roots and the cadmium inhibition effect of the iron film are weakened, wherein the alkaline passivatorOff-state Fe downstream of passivator application conditions²⁺The concentration drop is one of the key factors, even if a small amount of Fe is added to the passivating agent²⁺Iron is also less effective due to the strongly basic nature of the passivating agent. Based on the assumption, a combined cadmium reduction method for rice field basal application passivator viability reduction and additional iron fertilizer root control in the tillering stage is invented through multi-point field test verification.

Disclosure of Invention

The invention provides a combined cadmium reduction method for applying lime to paddy rice at the base and additionally applying iron fertilizer to soil in the early tillering stage of paddy rice aiming at the technical requirements of safe production of low-and-medium-cadmium-polluted farmlands. For acid medium-light cadmium soil exceeding the standard, the method integrates the functions of reducing the activity of cadmium in the soil by applying alkaline passivators such as lime and the like and increasing the cadmium resistance of an iron film on the surface of a rice root by additionally applying Fe fertilizer in a key period. For acid soil with medium and light cadmium exceeding the standard, compared with the control, the lime base application alone, the iron fertilizer dressing alone and the lime and iron fertilizer mixed base application treatment, the cadmium concentration of the brown rice of the rice is respectively reduced by 74.6-75.4%, 52.6-57.1%, 66.7-69.4% and 45.5-51.6% by the combined reduction and segregation method.

The acid soil heavy metal passivation material is generally strong in alkalinity, is directly applied to rice leaves or is unevenly applied, possibly causes damage to rice growth, and is generally applied as a base based on the needs of farm work. The base application of the passivating material can effectively reduce the bioavailability of cadmium in soil and reduce the absorption of cadmium by rice, but relatively speaking, the absorption of heavy metals in the rice seedling stage is less. The tillering-booting stage is the main stage of the rice vegetative growth, the root system grows rapidly, and the rice root system absorbs and accumulates nutrient elements and also absorbs and accumulates heavy metal ions in large quantity. Most of rice soil in south China is acidic, the activity of iron in the soil is high, the application of the passivator improves the pH value of the soil, reduces the effective cadmium content of the soil, reduces the effectiveness of the iron, and inhibits the formation of an iron film on the surface of rice roots and the cadmium resistance of the iron film to a certain extent. The tillering-booting stage is a key stage for forming the iron film on the rice root surface, the iron fertilizer applied to the soil in the tillering stage is high in effectiveness, the formation of the iron film on the rice root surface is facilitated, and the absorption of cadmium by the rice is prevented and controlled.

The technical scheme adopted by the invention is as follows: a cadmium reduction method combining the reduction of activity of a rice base application passivator and the root control of an iron fertilizer applied in a tillering stage is to apply 100-plus-alkali passivating materials at a base for 300 kg/mu 1 week before the sowing or transplanting of rice; and (3) when the rice grows to a tillering stage, keeping the soil to be in a semi-moist state, dissolving 7.5 kg/mu of iron fertilizer in water, uniformly spraying the iron fertilizer on the surface of the soil or mixing with additional fertilizer, applying the iron fertilizer and the additional fertilizer to the soil, applying the fertilizer for 2 days, keeping the water flooding to a milk stage or later, and harvesting after the rice is mature.

In the method, the specific dosage of the basic application alkaline passivation material is determined by the pH value of farmland soil: the pH value is less than or equal to 6, and 150-300 kg/mu is applied; the pH value is more than 6 and less than or equal to 6.5, and 100-150 kg/mu is applied.

The alkaline passivation material can be quicklime, slaked lime, limestone powder, caustic sludge and the like.

The iron fertilizer is preferably FeSO₄. The application period of the iron fertilizer is preferably the early tillering period of the rice, namely the second tillering period begins to appear.

The invention compares the effects of a plurality of methods, and test results show that the cadmium content of the brown rice can be reduced by the plurality of methods. Compared with the contrast, the cadmium concentration of the brown rice is respectively reduced by 42.6-46.5%, 19.7-23.9%, 49.2-53.5% and 74.6-75.4% by the combined method of independent base application of lime, independent additional application of iron fertilizer, lime and iron fertilizer mixed base application, base application of lime and tillering stage additional application of iron fertilizer, wherein the activity reduction of the base application passivator and root control of the tillering stage additional application of iron fertilizer are optimal, and the cadmium concentration of the brown rice is reduced by 52.6-57.1%, 66.7-69.4% and 45.5-51.6% compared with the treatment of independent base application of lime, independent additional application of iron fertilizer, lime and iron fertilizer mixed base application.

The method of the invention not only overcomes the defects that the iron activity in the soil is reduced due to the base application of the passivating agent, which is not beneficial to the formation of the iron film on the surface of the rice root and the cadmium resistance; but also overcomes the defect of only applying iron fertilizer (FeSO)₄) The problem that the effectiveness of the cadmium in the soil cannot be effectively reduced is solved, and the cadmium reduction effect of the rice can be effectively improved. The method is simple and easy to implement and has low cost.

Detailed Description

Example (b): (Jiangxi Guixi, Anhui Tongling)

Planting a variety of Meixiangxinzhan (Jiangxi Xinjiang province Co., Ltd.) in Jiangxi Guixi rice field with the pH value of 4.9 and the total cadmium of 0.75 mg/kg; the variety is Yuanyangyou Huazhan (Yuanying agriculture high-tech Co., Ltd.) planted in the Culing rice field of Anhui province with the pH value of 5.6 and the total cadmium of 0.62 mg/kg. On the basis of applying 200 kg/mu lime on the foundation, 7.5 kg/mu FeSO is applied at the early stage of tillering₄And after 2d, keeping the field flooded to the milk stage, harvesting after the rice is mature, wherein the test results are shown in the table 1:

TABLE 1

Note: all groups in the table were identical in other conventional cultivations except for the different treatment methods.

In the above 2 kinds of acidic rice soil with medium-light cadmium exceeding standard, the cadmium concentration of the contrast-treated brown rice exceeds about 3 times of the national food safety limit standard (0.2mg/kg), and serious human health risks exist. The cadmium concentration in the brown rice can be reduced by singly applying lime as a base or by singly applying an iron fertilizer in the tillering stage, but the cadmium concentration in the brown rice is 0.35-0.54mg/kg and still exceeds the national food safety limit standard. The cadmium reducing effect of the mixed base application of lime and iron fertilizer is slightly better than that of single application treatment, and the cadmium concentration of the brown rice is 0.31-0.33mg/kg but still exceeds the standard. And alkaline materials such as lime and the like are applied on the base, and the iron fertilizer is applied in the tillering stage, so that the cadmium concentration of the brown rice can be obviously reduced to 74.6-75.4%, the concentration of the brown rice is 0.15-0.18mg/kg, the brown rice meets the national food safety limit standard, the brown rice can be safely eaten, and the yield is slightly increased compared with the reference.

The examples show that the Cd content of the brown rice can be effectively reduced by applying alkaline passivation materials such as lime and the like to the base in the medium-light acidic rice soil with excessive cadmium and additionally applying a proper amount of iron fertilizer at the early stage of tillering of the rice.

Claims

1. A rice basal application passivant viability reduction and topdressing iron fertilizer root control combined cadmium reduction method in a tillering stage is characterized in that: applying 100-300 kg/mu of alkaline passivation material to the base 1 week before sowing or transplanting the rice; and (3) when the rice grows to a tillering stage, keeping the soil to be in a semi-moist state, dissolving 7.5 kg/mu of iron fertilizer in water, uniformly spraying the iron fertilizer on the surface of the soil or mixing with additional fertilizer, applying the iron fertilizer and the additional fertilizer to the soil, applying the fertilizer for 2 days, keeping the water flooding to a milk stage or later, and harvesting after the rice is mature.

2. The method of claim 1, wherein the iron fertilizer is FeSO₄。

3. The method according to claim 1, wherein the iron fertilizer is applied at a stage prior to tillering of the rice, i.e. when a second tillering begins.

4. The method of claim 1, wherein the specific amount of the basic passivation material applied is determined by the farmland soil pH: the pH value is less than or equal to 6, and 150-300 kg/mu is applied; the pH value is more than 6 and less than or equal to 6.5, and 100-150 kg/mu is applied.