What is the relationship between climate and agriculture?
As an environmental factor and natural resource, climate has many influences on agriculture:
(1) Climate factors such as light, heat and water are the basic factors that determine the planting system, among which heat is the dominant factor that determines the four seasons in a certain area. Generally speaking, the accumulated temperature ≥0℃ in three seasons of a year is higher than 5900 ~ 6100℃; It is required that the accumulated temperature ≥0℃ in two seasons a year should be greater than 4000 ~ 4200℃; In areas with accumulated temperature ≥0℃ and less than 4000 ~ 4200℃, it can only be used once a year.
(2) Different combinations of climatic factors such as light, heat and water have different effects on agricultural production. Light, heat, water, etc. Provide energy and materials needed for crop growth and development, and their different combinations have different effects on agricultural production. For example, in the southeast of China, light and heat are in the same season, and the water conditions are good, which is conducive to increasing agricultural production; The Qinghai-Tibet Plateau is rich in light and insufficient in heat, which is not conducive to high agricultural yield. The northwest region is rich in light, but insufficient in water, which is not conducive to increasing agricultural production.
(3) Regional differences in natural productivity of land resources are mainly caused by regional differences in hydrothermal conditions. The biomass of arid and semi-arid areas in the west, which accounts for more than 50% of the country, only accounts for13% of the country; The eastern area is less than 1/2 of the whole country, and the biomass accounts for 87% of the whole country. This difference in natural productivity of land resources between the east and the west of China is mainly caused by the difference in water conditions between the east and the west. The biomass in the eastern region is decreasing from tropical to cold temperate zone, with a difference of 5 ~ 6 times between north and south. The north-south difference in natural productivity of this land resource in the eastern region is mainly caused by the difference in heat conditions between the north and the south.
(4) The variety and quality of crops are closely related to climatic conditions. The types of crops suitable for growing in a certain area are closely related to the local climatic conditions (temperature, humidity, etc.). ). For example, northern China is suitable for planting crops that like long sunshine and cool climate; The south is suitable for planting crops with short sunshine and sufficient heat.
Of course, the climate also has a certain impact on the agricultural production environment.
Climate change mainly affects agriculture through temperature, precipitation, carbon dioxide concentration, extreme weather and climate events, and varies with regions and seasons. Generally speaking, the impact of climate change on agriculture in China has both advantages and disadvantages, but it is mainly negative.
Atmospheric-climate warming is mainly caused by the increase of greenhouse gases emitted to the atmosphere by human activities, in which carbon dioxide is one of the main greenhouse gases, and its warming contribution accounts for more than 1/2 of all greenhouse gases. With the increase of carbon dioxide concentration, the carbon dioxide exchange rate, net assimilation rate, biomass and yield of most crops increased, while stomatal conductance and transpiration decreased accordingly. Therefore, its direct function is conducive to improving the photosynthetic utilization rate of crops and increasing crop yield.
Soil-climate change leads to the increase of soil microbial activity, the loss of soil organic matter and nitrogen, the acceleration of soil degradation, erosion and salinization, and the weakening of agricultural ecosystem's ability to resist natural disasters.
For agricultural production methods, the influence of climate is also to a certain extent.
Adjustment of cropping system-Due to the change of regional heat conditions, climate change has impacted the long-standing agricultural production pattern and cropping pattern in China, especially in low latitudes, but it has brought the possibility of developing multiple cropping system in middle and high latitudes and plateau areas.
Aggravation of pests and diseases-Climate warming will aggravate the prevalence of pests and diseases and the spread of weeds. At present, there are some pests and diseases in northern China, especially in spring and autumn.
Climate warming has intensified the spread of pests and diseases.
Increased agricultural cost and investment demand-Climate change leads to an increase in agricultural input to reduce negative impacts and improve agricultural production environment.
Extreme weather increases and losses increase-global temperature rises unevenly, which affects the thermodynamic mechanism of the global weather system, thus causing changes in the time and distribution of extreme weather events and increasing the frequency and intensity of disasters. Extreme climate is an important factor leading to the sharp reduction of agricultural production and the fluctuation of grain output in China.
Climate change also affects the development of crops as raw materials of biomass energy. Biomass refers to all renewable substances from animals and plants except fossil fuels. Biomass energy is the energy contained in biomass, which is the energy stored in biomass by green plants to convert solar energy into chemical energy through chlorophyll, and is also often called bioenergy. The influence of climate change on crops is manifested in the influence of the increase of carbon dioxide concentration on the physiological functions of crops, the influence of the change of average temperature on the performance and distribution of crops, and the influence of precipitation and radiation on the growing season, growth period and yield of crops.
The whole process of agricultural production is carried out under natural conditions, which is bound to be influenced by natural conditions such as climate, soil, topography and vegetation, especially meteorological conditions. Because the change of weather and climate conditions in time can make agricultural production have obvious seasonality, while the change in space makes agricultural production have obvious regionality. Therefore, agricultural production must vary with time, place and crop. It can be said that climate change has brought both opportunities and challenges to agriculture in China. How to deal with climate change has become an urgent problem. Therefore, under the condition of climate change, it is an inevitable way to adjust the agricultural production structure in time, develop new adaptive technologies and develop ecological agriculture construction.