I like it! May be it is worth adding some other grass, not just yellow flowers and basic green? 
It looks like a flower bed, not like a meadow this way.
Next render, could you please elaborate on the grass bit? I thought it looked fine and no one else commented on it.
Hi! very nice!
I’m just going to criticize observational things, because I don 't know how you can do all that!
The river: The border of the river are completly dry, that can’t be. water climb because of the superficial tension that create the capilarity, so earth just drink water just by contact it. so it goes up. You have to darken (soils wet are normaly darken that the dry ones) up to 15 cm more or less.
Air: that sims a spring day, and there are no flies or pollen or birds, or anything flying! and that makes me uncomfortable! hahaha.
Also some mist pass can help.
Overall a good start, you have most of the pieces but they aren’t assembled in a truly convincing fashion. Starting with the far background:
1)The horizon at the right is unnaturally even, like a clipped hedge almost. It needs some irregularity, even raggedness. This is also true for the evenness of the row of bushes along the river, real undergrowth like that is very randomly distributed. The river banks are of the same kind of artificially even form, like groomed lawns where flowers have been planted. All the same flower also, no weeds, none varying from a very similar average size. Nature is much, much messier than that.
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In general the trees are not bad but there are a few features that challenge the sense they are real. That in the BG has limb growth that seems too dense for a tree of that age/height. The trunk(s) and main branches are much too thick at the base and taper too fast. The branches growth pattern looks more artificially random than according to typical growth patterns. This is not to say trees don’t display some randomness in growth patterns, but they all grow according to genetically-determined plans of branching – there is always some order underlying the apparent chaos. The FG tree leans a lot, not unusual, but coupled with the odd trunk shape – too thick at the base with a very fast taper – it looks again, artificial. The bark looks good but since there isn’t much in the way of clues to the species of the tree, it’s hard to say if it’s appropriate, and it looks somewhat overly rough for a tree of that age (as judged by height). Younger trees have more regular bark patterns.
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The colorations and lighting are very good and go a long way to making the scene more convincing, keep that up! The river water is coming along nicely in terms of the surface but needs a lot more happening along the banks – the soil/dirt there looks bone dry, the density of plant growth decreases when it should increase and change its character (plants love water!), and the banks are entirely too even, as if artificially landscaped. In the extreme FG, the variety of plant types is much too limited and its growth unnaturally regulated, as if mowed regularly.
Time now, I think, to indulge in some study of tree and plant species to find out which might inhabit this scene and how they would present themselves on a high-summer’s day like this. It would do much to improve the believability of the image. There is an incredible number of images on the web that can be used as refs, maybe start a trees/plants folder?
These comments are to the image in Post#22, btw