What is the Minimum Plant Available Water to Grow Maize?

Maize, also known as corn, is one of the most important crops in the world. It is a staple food for millions of people, livestock feed, and raw material for various industries. Maize requires adequate water supply to mature and produce high yields. But what is the minimum plant available water (PAW) that maize needs to grow? In this article, we will explore the answer to this question.

What is Plant Available Water?

Plant available water (PAW) is the fraction of soil water that plants can use to grow. It is the difference between the total soil water content and the lower limit of soil water availability. Soil texture, structure, organic matter, and other factors determine the plant available water capacity of a soil.

Plant roots absorb water from the soil, and the amount of water that roots can extract is limited by factors such as water potential, soil tension, and root distribution. The PAW is the amount of water that satisfies the plant's transpiration and other growth needs without causing water stress.

Maize Water Needs

Maize is a C4 plant that has a high demand for water during the vegetative and reproductive stages. Water stress can affect leaf area expansion, stem elongation, and kernel development, resulting in reduced yields and lower quality of grain. Maize production regions require different amounts of water, depending on their agro-climatic conditions, soil types, and management practices.

According to research, maize requires about 450-500 mm of water during its growing cycle, with the bulk of the water consumed during the reproductive stage. This amount of water translates to 630-700 mm of rainfall, assuming a runoff rate of 30% and a water storage rate of 70%.

Minimum Plant Available Water for Maize

Studies have shown that the critical PAW for maize varies depending on the region, soil type, climate, and cultivar. Generally, maize requires a minimum of 50% of the PAW to be available for optimal growth and yield. Maize can still survive with lower amounts of plant available water, but the yield potential and quality of grain will be affected.

The crop coefficient (Kc) is a factor that determines the amount of water that a crop needs per unit area. The Kc values for maize range from 0.8 to 1.2 during the vegetative stage, 1.2 to 1.4 during the reproductive stage, and 0.6 to 0.8 during the maturation stage. This means that during peak demand, maize can consume up to 6 mm of water per day from the soil.

Conclusion

In conclusion, maize requires a minimum of 50% of the plant available water to achieve optimal growth and yield. The amount of water required depends on the prevailing agro-climatic conditions, soil type, and management practices. PAW is a critical component of soil fertility and crop productivity, and farmers should ensure that soil moisture is adequate for their crops to grow and mature.