Is it better to irrigate a field in the morning or evening?

Question

Is it better to irrigate a field in the morning or evening?

Answer 1

I'm going to buck the trend here and tell you to irrigate in the morning (especially turf!).

The reason is that when you irrigate in the evening the foliage is going to stay wet all night.  The moisture on the leaves in combination with the cooler night temperatures creates a prime condition for fungal diseases to infect the leaves.  If you are talking grass, you are opening yourself up to Grey Leaf Spot, Dollar Spot, Leaf Rust, and a whole host of other diseases.  In crops, depending on the disease and severity, yields can be reduced 10-50%.  

Irrigating in the morning allows the leaves to dry off more quickly reducing optimal period of infection.  

One of the biggest mistakes people make with irrigation (again especially on turf) is they don't put on enough water and do it too often.  By watering a little bit every day, the water never soaks down into the ground.  The root system is going to stay where the water is, so it also stays shallow.  The one day (or week) you don't water, the top couple of inches of soil completely dries out and the plants are in drought stress.  The alternative is to water several inches and allow it to soak into the ground once or twice a week.  This encourages the roots to go deep and seek out the water held in deeper soil which does not dry out as quickly.

If you are concerned about evaporation, irrigate in the early morning (just before sunrise).  This will give the water plenty of time to soak in (as much as it is going to) before the heat of the day.

Answer 2

Always irrigate, water lawns, etc in the evening.

Answer 3

it is best to irrigate in the evenening so that the sun will not evaporaate a bunch of your water, if you do it in the morning as the day gets warmer your water will evaporate and not soak into the ground as much

Answer 4

evening is better because the sun wont evaporate it and it has all night to soak up.

Answer 5

EVENING LESS EVAPORATION

Answer 6

much better to irrigate in the evening because temps are cooler therefore you wont lose as much to evaporation and also if temps are in the 90s or hotter it is possible to scold the roots on the plants

Answer 7

You said "field", this must be farm and not lawn as some of the friends describe in their answers.

If it comes to irrigation of fields, it is better to start at around 4 in the afternoon.

Reasons are:

1). You must complete the job say by 7 or 8 pm.

2). (Depending on source) water is warmer by soaking day's sun; hence it has reduced surface tension.

3). Water with reduced surface tension is better in spreading underground as well as absorption by the plants.

4). Field will require less water for above reason.

5).Reducing chances of evaporation. (Evaporation cannot be totally skipped, since earth remains warm even as sun goes down. Moreover; one experience drying process whether sun is there or not.).

Answer 8

This paper reports the effects of irrigation regime and partial rootzone drying (PRD) on water relations, yield and wine quality of ‘Tempranillo’ in a deep, light-clay soil during two consecutive years with contrasting crop loads. PRD was compared to conventional drip irrigation at two levels: 50% and 100% of estimated crop evapotranspiration (ETc) and also to a non-irrigated treatment. Under our experimental conditions, Tempranillo showed a tight stomatal control in response to dry soil and to air VPD, that maintained irrigated and rain fed plants, at similar leaf and stem water potential values at midday. Thus, determinations of water potential either at predawn or early in the morning reflected better actual plant water status than those at midday. PRD, compared to the conventional irrigation, had no effect on water relations, neither yield nor wine quality in both years. The effects of irrigation amount on yield and wine quality were different between years. With low crop load (3.8 kg/vine) irrigation did not affect yield neither wine quality. However, in the second year, with high crop load (10.3 kg/vine), irrigation allowed for a 29 % increase in yield, and it also increased must total soluble solids and wine alcohol content. Other wine quality parameters like total phenols and anthocyanins were not significantly affected by irrigation level and only pH increased with irrigation. Our results suggest that moderate irrigation rates (500-600 m3/ha) can substantially increase grapevine production without affecting wine quality.

Under all forms of high-frequency irrigation of fruit trees, the questions concerning irrigation management are not when to irrigate but rather how much to apply and how to accurately evaluate the water status of the tree. Leaf water potentials (psi sub L) offer a reliable means to evaluate the water status of apple trees if the values are adjusted to compensate for diurnal and daily changes associated with weather changes. A strong linear relationship suitable for field use has been found to predict psi sub L from a known atmospheric vapor density gradient (delta rho sub va) where stomatal conductance is high for both nondeficit and deficit irrigated trees. The slopes of linear equations for trees grown under nondeficit and deficit irrigation regimes differ significantly which indicates that conventional predawn measurements of psi sub L are not adequate for establishing the plant water status of apples. This relationship appears to be independent of the type of irrigation system. A late morning reading more accurately reflects the plant water status rather than the soil moisture status and is a better indicator of deficit irrigation levels. (Collier-IVI)

... either at predawn or early in the morning reflected better actual plant water status

than those at midday. PRD, compared to the conventional irrigation, had no ...

http://www.actahort.org/books/754/754_40...

Answer 9

Irrigate in the morning.  

Other than fungus etc., that you are avoiding, remember its easier to see field and stuff during the day.