Climate change poses a major challenge for agriculture, especially in regions that experience frequent droughts and heat waves.
To ensure food security and sustainability, farmers need to adopt practices that can help their crops adapt to changing weather conditions and reduce greenhouse gas emissions.
A new study from the University of Missouri and the United States Department of Agriculture (USDA) has investigated how different farming systems affect the water and carbon cycles of staple crops like corn and soybeans in Missouri.
The study was published in Agriculture and Forest Meteorology.
How water and carbon cycles are linked in plants
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One of the main reasons plants use water is to allow them to absorb carbon dioxide from the atmosphere through a process called photosynthesis, as per Phys.org.
Carbon dioxide is then converted into organic matter that forms the basis of plant growth and biomass. This means that in plants, the water and carbon cycles are tightly linked, and any changes in one cycle can affect the other
The researchers used a tool called eddy covariance tower, which measures the exchange of water vapor and carbon dioxide between the land surface and the atmosphere, to monitor three contrasting ecosystems: a conventional tilled cropping system, a no-till cropping system with cover crops, and a native tallgrass prairie ecosystem.
The study spanned four years, from 2016 to 2019, covering different weather patterns and crop rotations.
How farming practices affect crop resilience to climate change
The study found that the native prairie ecosystem had the highest rates of evapotranspiration, which is the sum of evaporation from the soil and transpiration from the plants, as per the University of Nebraska-Lincoln.
Evapotranspiration is an indicator of how much water is used by an ecosystem, and also affects its temperature and humidity.
The native prairie also had the lowest rates of carbon dioxide uptake, meaning it had less plant growth than the cropping systems.
The tilled cropping system had lower rates of evapotranspiration than the native prairie, but also lower rates of carbon dioxide uptake.
This suggests that this system is less efficient at using water for photosynthesis, and more vulnerable to drought stress.
The tilled system also had higher rates of carbon dioxide emission from the soil, which contributes to greenhouse gas emissions.
The no-till cropping system had similar rates of evapotranspiration as the native prairie, but higher rates of carbon dioxide uptake than both the native prairie and the tilled system.
This indicates that this system is more efficient at using water for photosynthesis, and more resilient to drought stress.
The no-till system also had lower rates of carbon dioxide emission from the soil than the tilled system, which reduces greenhouse gas emissions.
The researchers concluded that the no-till cropping system with cover crops is a promising practice for enhancing crop resilience to climate change and mitigating greenhouse gas emissions in Missouri agriculture.
They also suggested that increasing crop diversity and incorporating perennial crops could further improve water and carbon cycling in agro-ecosystems.
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What are some benefits and challenges of no-till farming?
No-till farming is a cultivation technique that avoids plowing and disturbing the soil, leaving crop residues on the surface as mulch.
No-till farming has several benefits for soil health, water conservation, climate mitigation, and crop productivity. Some of these benefits are:
Reduced soil erosion: No-till farming protects the soil from wind and water erosion by maintaining a cover of organic matter on the surface. This helps preserve soil structure, fertility, and biodiversity.
Increased water infiltration and retention: No-till farming improves soil porosity and reduces runoff by allowing more water to infiltrate into the soil. This also reduces evaporation from the soil surface, keeping it moist for longer periods.
Enhanced soil organic matter: No-till farming slows down decomposition of organic matter by reducing soil disturbance and aeration. This helps increase soil carbon storage, which improves soil quality and fertility.
Lower fuel and labor costs: No-till farming reduces the need for machinery, fuel, and labor for tillage operations. This also reduces wear and tear on equipment and machinery maintenance costs.
Higher crop yields: No-till farming can improve crop yields by creating favorable conditions for plant growth, such as better soil moisture, temperature, nutrient availability, weed suppression, and pest control.
However, no-till farming also faces some challenges that may limit its adoption or effectiveness. Some of these challenges are:
Equipment cost: No-till farming requires specialized equipment for planting seeds through crop residues without disturbing the soil. This equipment can be expensive to purchase or modify.
Weed management: No-till farming relies heavily on herbicides for weed control, which can increase input costs and environmental risks. Alternatively, organic no-till farming uses cover crops or mulches to suppress weeds, but this may require more management skills and labor.
Pest and disease management: No-till farming may increase the risk of pest and disease outbreaks by creating favorable habitats for some insects, fungi, and bacteria. For example, crop residues may harbor insect pests or fungal pathogens that can infect the next crop. Crop rotation and biological control may help reduce these risks.
Nutrient management: No-till farming may affect nutrient availability and cycling in the soil, depending on the type and amount of crop residues left on the surface. For example, high-carbon residues may immobilize nitrogen and reduce its uptake by plants. Fertilizer application and timing may need to be adjusted to optimize nutrient use efficiency.
