I heard about using alternate forms and test-retest to estimate reliability. But due to lack of resources, I cannot afford to write two tests or administer the same test in two different times. On the other hand, KR can be applied to dichotomously-scored data only. But if your test is composed of essay-type questions and each question worths 10 points, then the scale is ranged from 0 to 10. In spilt-half, you treat one single test as two tests by dividing the items into two subsets.
Reliability is estimated by computing the correlation between the two subsets.
For example, let's assume that you calculate the subtotal scores of all even numbered items and the subtotal of all odd numbered items. You can simply calculate the correlation of these two sets of scores to check the internal consistency. If the correlation of the two sets of scores is low, it implies that some people received high scores on odd items but received low scores on even items while other people received high scores on even items but received low scores on odd items. In other words, the response pattern is inconsistent. The drawback is that the outcome is determined by how you group the items.