I would suggest a few things from my grass tests
Make more clumps of grass in different sizes and height, try to stay in real world blade scale - I think the more clumps you make with the transformation tool of FP Pro the better your result will be.
I like to make clumps with growfx - as they are easily editable even after scattering over small surfaces and also assign different matIDs to them to have control over color variation
Use corona multimap with different tones of blades and with distribution by material ID
Also you can use Forest Pack clumping option which should simulate real world grouping of same plants. Even inside Forest Pack there is an option to pick random color values either from gradient or from any map - this adds to color variation.
Last but not least I would suggest adding small plants that usually grow with the grass - just browse over some grass photos and try to analyze what is going on there
Also maybe your shader needs a bit more tweaking to find the right balance between diffuse, reflection and translucency