It’s California’s Central Valley. If we don’t irrigate in the summer we have only dry grass. We used to try and irrigate every three weeks. Now we have the soil moisture sensors to help with the decision.
There are two sensors. The both show moisture at 4″(green), 8″(purple), and 12″ (blue) depths. The dark colors are the west sensor and the light colors are the one more towards the east. Red is water flow through the system when we irrigate. I’m showing three months for perspective. Notice the green lines rising (more on the west) in the middle of April. My records show 1″ of rain followed by 1.5″ about ten days later. I didn’t record the one in early May. So that amount of rain impacted the top layer of the soil, but doesn’t do much for the lowest level
It should rain in March, but it did not. When we irrigated in late March we had more water than we could use. We had asked for a certain time period and had to pay for that amount of water whether we needed it or not.
There are problems with too much water:
1. We are paying for what we don’t need.
2. Farms are given an allocation at the beginning of the season based on irrigated acreage. We don’t know what the weather will be like through the year. It was unusual for the irrigation district to fill the canals and offer water in March, but farmers needed the water. However, now that allocation has to last us until we get rain again.
3. Just as in your garden you don’t want plants to be underwater and flooded for too long.
4. Mosquitoes!
So when it came time to irrigate again, we had probably waited a little too long. We asked for the same amount of water (1-1/2 acre feet) but for less time. This is the story I told about that irrigation. Part 1.and Part 2. There was a big problem. It took all day to get across short checks on the north and we were able to get the water back in the pipeline two days later to finish and the water tender said he’d give us more. The graph below shows that sequence a little better. When you compare it to the graph above it looks as though the amount of water the sensor measures on May 18 is less than for the March irrigation, but I’m surprised that it made that much difference.
So here we are three weeks later. Look at the green lines on that graph. We asked for 2′ of water for about 28 hours.
This is the canal that flows into our system.
This is where Dan had added tractor loads of compost to the lane at the south end of #7 North. That has seemed to be a low spot, the water from the north stays there, and the valve for the south part (you can barely see it where the black plastic post is) flows backwards into the low spot.
Those top seven checks were fully irrigated before noon and I was ready to open the valves to the south. Then I found myself wanting to deal with the dry grass that was serving as a mulch on those north paddocks. We don’t need the clover and trefoil covered ups with mulch.
This seems ridiculous but I took a large rake out there and attempted to rake the dried grass off the pasture. I know I did this last year. The grass was floating and I could rake piles. This time it was different. A although Dan had mowed, only a fraction of this is that superficial grass. A lot is still rooted. Not that it will grow again, but it’s more difficult to remove.
You can see the difference in upper part of the photo. It’s bothering me that so much of some of these paddocks are not as productive as they should be. This is the result of the ryegrass that took over last spring and again this spring. I need to be able to graze these before the grass gets so tall that it is trampled and flattened more than eaten .
I did rake some and made loads with the wheelbarrow before I decided that this was a dumb idea and I could never make much of an impact.
Moving to the south, there is a flooding issue at #8. One of the ways to control this is to have more valves open and lessen the water pressure. Remember, this was more water than. before. I’m learning as we go along. I used the wheelbarrow and took some of that fill that was near #7 and made a border here.
Later that evening I saw that with this much water #11 and #12 flood the lane at the barn.
Almost all the lower paddocks were finished by the evening. I opened the last three around 6 p.m. The water wouldn’t be turned off until the SID water tender was on site at 6 a.m. It still flows into our ditch for another hour after that.
Here’s a closer view of yesterday and today. We’ll need a better plan next time.
I irrigated this weekend. The sheep were just moved off the paddock to the right and when it dries up enough they will go on the one to the left. Can you see the difference? It took only two days for them to eat that feed.
One of their favorite plants is Birdsfoot Trefoil. It is a legume which means it is one of the plants that converts nitrogen in the air to a form that can be used by the plant. It is actually not the plant that does that but the bacteria that live in nodules on the roots of legumes.
Clovers are also legumes. This is a variety of white clover.
This morning I noticed just a few of these flowers. I can’t decide if this is a variant of the white clover or is a different species. The leaves are similar. I’ll have to do some more checking.
Do you see how most of the other plants have been eaten and this one has not been touched? The sheep avoid plants that are toxic to them. This is Narrow-leaved Milkweed (Asclepias fascicularis). Not only is it a favored species for the monarch butterfly but according to a 
These are Narrow-leaved Milkweed flowers in various stages…
…and a close-up.
Field bindweed (Convolvulaceae arvensis), also known as morning glory. It is, according to a 
Soft Chess or Soft Brome, a non-native annual grass.
Medusahead as it is drying out. Medusahead covers thousands of acres of California foothills. It is not normally found in irrigated pasture, but it is in the easternmost paddock here which sometimes does not irrigate well. I have reclaimed part of that paddock, but I continually fight this plant. I find patches of it in other areas of the pasture and, although this is not an effective control technique, I pull it up by the handfuls as I walk by, coming back to the barn with it stuffed in the pockets of my overalls. It is a nasty plant that is “…among the worst weeds: not only does medusahead compete for resources with more desirable species, but it changes ecosystem function to favor its own survival at the expense of the entire ecosystem…Because grazing animals selectively avoid this plant, and because medusahead thatch tends to suppress desirable forage species, infestations often develop into near-monotypic stands.” From the 
I have ID’d this one as Blunt Spikerush (Eleocharis obtusa), not a grass, but a sedge that is found on poorly drained soil and marshy areas. That’s my pasture…poorly drained soil. There is a lot of this sedge in the middle and south end of three or four of the paddocks. It looks like foot-tall grass, but that is why it is important to actually look at what is out there. This does not make good forage.
A rather artsy shot of Buckhorn Plantain, found throughout California…
…and a photo in which you will probably more easily recognize it.
This is the ditch that runs north-south and brings the water from the upper ditch to the one that goes from west to east along the bigger pasture.
This photo is looking the same direction but from a little bit west of the first one. You can see the same row of overgrown blackberries along the fence. The standpipe where the water comes in is in the upper left corner. In the lower center of the photo is one of the cut-outs that lets the water flow from the ditch into the field.
Looking to the east as the water is flooding the pasture from north to south. In this photo the water hasn’t gotten very far into the paddock where the sheep are.
Here is that tarp I showed in the last post.
There are things to see besides just water and grass. One of the first things I noticed after the water filled the ditch was buzzing. These insects were everywhere over the water. I tried to ID it on the internet but didn’t find it. Anyone know what this is? 
This is one of the pair of Swainson’s hawks that lives nearby and hunts in our pasture.
We have enough gophers to feed an army of hawks.
This was taken from standing in the northwest corner of the property and looking west. When SID (Solano Irrigation District) opens the right gate the water comes down that canal, through a gate in the cement structure at the bottom of the photo and…
…comes up through this standpipe. It goes out that hole on the left and…
into this ditch. At the end of the ditch it turns south and goes into the other part of the pasture. Later in the year this ditch will require weed-wacking for the whole length to allow the water to flow. This time I didn’t need to do that.
This part of the ditch has old pipes that take the water under the burm. I can find two of the three that used to be functional.
The first job is to dig out around both ends of these.
As I walk through the pasture I find thistles that need to be chopped.
The rest of the pasture doesn’t have those pipes, but instead has cut-outs or places where the burm is cut away to allow the water to flow from the ditch into the pasture. I didn’t get photos of those. This photo is a cut-out (under the fence) that I had to fill in because it was where we had cut through the burm to allow water flow INTO the ditch in the winter to help drain the rainwater that was all around the barn. 
Here is the place at the northeast corner of the pasture where I have to put a tarp to keep the water backed up in the ditch. After this point the ditch turns south and drains at the southeast corner of the property.
I can never remember what size tarp to get. I bought 2 sizes and took this photo to remind myself that this one is just fine.
The idea is to set the tarp so that the edges are buried in dirt and those boards behind will keep the water from pushing the tarp down flat. I did this twice. 
The first time the dirt that holds the tarp down on the bottom was too high. That means when I released the tarp at the end of irrigating there would still be a dam. I have a hard enough time getting the ditch to empty that I don’t need to impede it more.
This is a second tarp that I set just around the corner in the ditch that goes south. I shouldn’t have to do this, but due to gopher holes, tree roots, and maybe my lack of irrigator skills it seems that one is never enough. Two tarps hold the water back better. Or at least one is a back-up for the other.
While I was working in the pasture I saw that a couple of lambs had their heads through the electric net fence and didn’t seem to care. That prompted a search for the problem with the electric fence. I found a broken wire at the south end. I got new wire and fixed it but then found several more places where I had joined new wire to old. The more times you do that the less conductivity there is. So I took out a long stretch of the old pieced-together wire and replaced it. Low and behold, my tester showed higher strength than it has in years!
One thing leads to another. While I was at that end of the pasture I was bothered again by the old dallisgrass that effectively mulches my pasture. It’s one thing to mulch a garden to keep weeds from growing, but mulching a pasture is counter-productive. If you search dallisgrass in this blog you’ll find many attempts to deal with this. This time I was simply knocking it off the electric wire that is about a foot and a half up on inside this fenceline. It broke and pulled away so easily at this time (this is last year’s dry grass) that I started pulling it away by the armfuls. I didn’t have any tools or even gloves, but threw mounds of it over the fence–hey, I’ll mulch the outside of the fence and maybe keep the growth down there. That felt somewhat productive although it may not be useful at all. But at least I could see a difference in the before and after.
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