The second one has a more successful perspective than the first, and I quite like the colour pallette. When doing your sketches though, try not to get caught up in unneccessary details like the fine grass brush that you used. A bit of texture to imply materials can help a sketch, but try and keep it loose - its all about the colour and light. Take a look at this sketch by artist Min Yum
, and see how he handles grassy areas. Notice how he implies a few blades of grass / reeds, but then letst the rest jsut become loose texture.
Of course, as soon as these are going to be matte paintings, this becomes largely redundant anyway as you will be working with photographs, but just to help you improve the presentation of your sketches a bit :)
Hope it helps, looking good! Hope to see more soon!