Sustainable Agriculture

Water - Too Much of a Good Thing?

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Water - Too Much of a Good Thing?

Water shortages or drought across the Prairies, can be a bit of a challenge for many farmers but the opposite is also true.  Too much water from excessive moisture can equally be as challenging.  Fields saturated with excess water cannot be easily entered at certain times of the year and can create delays in working or seeding them especially in the spring.  This of course results in missed cropping opportunities and can impact current yields.  But what about the excessive moisture - How much is too much and what can we do about it?

Finding Balance in the Water Cycle

It’s all about finding balance. Farmers are not only influenced by too much water, but also by the timing of excessive water and its impacts on agriculture.  Generally speaking water follows through our land as a cycle and needs balance within the system to work effectively. The same is true for agricultural water use.   Ideally we need to measure and manage water for our cropping systems, our land, and it’s dependent on our current conditions. 

Excessive water happens when we have high moisture levels in the fall, followed by rapid snowmelts, or heavy spring rains.  Much of our annual precipitation is taken up by crops in efforts to meet their needs.  Making our soils act as a sponge to soak up much of this water.  Some is used for plant uptake, and some water is saved for a “drier day.”  Sometimes we have too much water in the system to begin with, or sometimes too much is taken from the system which can result in water shortages in other times of the year.

An important part of the water cycle that all farmers should consider is the process of evapotranspiration.  Evapotranspiration usually occurs from June to September and is a combination of evaporation from the soil and transpirations from the crops.  It assists in creating a water surplus if the amount of precipitation is greater than the rate of evapotranspiration.  

And water surplus + excess water = and requires better drainage.  How might an excess of water impact my operations?

On the Short Term

Too much water in one area in the short term, takes longer for wet soils to warm up and thereby leads to potentially poor germination or stunted plant root systems.  But depending on the timing of excessive water it will too impact your operation in different ways.  

On the field, if plant growth has already started, too much water can flood the crop.  Called waterlogging, it simply starves oxygen from the root system and can lead to low productivity, underdeveloped roots, or even plant death.  It’s important to remember that depending on the species of crop grown, there can be various tolerance levels to excess water and saturated conditions.  Some crops are more sensitive to waterlogging and some are more tolerant.  Plant accordingly to your conditions.  

Characteristics of soil texture and topography of the landscape can also contribute to excess water in agriculture.  Coarse and medium textured soils drain faster than clay soils and are less affected by water saturation.  It’s the medium to fine textured soils, which exhibit the longer-term impacts of excess water. However Mother Nature also plays an important role in determining excess water.

 

On the Long Term

Too much water for too long can easily impact our soils by resulting in some or many of the following concerns.

Increased nutrient losses – increases in nitrogen gas and nitrous oxide, reduces microbial populations or the uptake of phosphorous, nutrient loss and leaching;

Soil compaction – impedes root growth and limits the movement of water;

Pests – increases in weeds, insects, and diseases compete with planted crops;

Soil crusting – can clog soil pores and reduce infiltration;

Pasture damage – damage from animal hooves on wet soil reduces Productivity, and in some cases leads to bare ground.

Soil erosion – the bare soils are susceptible to runoff and can leave deposits of sediments and excess nutrients in other places downstream.

And the list continues...  But the good news is we can use Best Management Practices (BMPs) as a start to help us deal with these longer-term effects.  

Best Management Practices for Excess Water 

Best Management Practices suggest planting cover crops grown alone or in mixtures as a protection from erosion.  In addition they also can begin to help improve the structure of the soil, the management of nutrients, and suppress potential pests.

In terms of nutrient losses, test your soil to determine the amount needed for your crop requirements based on soil type.  Apply 4R Nutrient Stewardship principles to minimize nutrient runoff.  Variable rate fertilizers can also be a wise choice for lowering the risk of runoff.  Proper tile drainage can also be an option.

Soil compaction occurs when wet fields are combined with heavy tractors and equipment traffic, which increase pressure on the surface of wet soils.  The air in the soil is basically forced out creating a more dense compacted soil.  Dual wheels or low-pressure tires can help assist with surface compaction. Remember, on wet soils – the heavier the load, the bigger the compaction.  It’s best to restrict access or wait for the soil to dry up before entering if possible.

Notice an increase in the number of pesky pests in the year, or years following excessive moisture? Try considering the addition of mechanical or chemical methods for managing them. Otherwise, you may be battling competition with your current crops.  

Avoid grazing on or near wet pastures until it dries out and can support livestock.  Also depending on the amount of excessive water received some re-seeding may be necessary.

Adopt erosion control methods such as increasing buffers, wetlands, grassed waterways, reduced tillage, runoff diversions etc. for managing erosion and runoff.  This can also help in reducing excess nutrient loss as well.

These are just a few solutions, which may be an option for you if you are battling excessive amounts of moisture, like so many others are this year.  And finally, our thoughts and support go out to the many Prairie communities in Manitoba and Saskatchewan currently being hit by too much water.  Hoping for a dry recovery back into the fields very soon.   Remember it’s not just about having water shortages and drought, too much water can also be a big concern.

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Diana Tyner (M.Sc.) is an environmental advisor, water guru, and licensed greenhouse gas quantifier.  She works with Canadian business, government, and industries to advance solutions in water, agriculture, and greenhouse gases. Diana's other blogs can been seen at at dianatyner.wordpress.com

 

Comments

Mazina KM
Diana, a very important issue which is neglected by most of the farmers. Mostly in rice feild this is a big issue. I would like to know more about 4R Nutrient Stewardship you mentioned.
Cheers, I love to read your blogs post.
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