A student designs an investigation to evaluate the effect of water acidity on the growth rate of potted spruce trees. What should be the independent variable in
the student's investigation?

this protocol provides a detailed procedure for agarose-based ip to purify and enrich the protein of interest.

1. loamy sand is about 80% sand with 10% clay and defined mostly by sand particles with some clay to provide structure and fertility. the sand particles are easily visible and the soil holds structure but breaks apart easily.

2. scott sand can improve his soil quality by incorporating more silt and organic matter into the soil. peat moss and organic matter can also be incorporated.

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