This does not apply to excreta-based fertilizers, which is an advantage. In intensive agricultural land use, animal manure is often not used as targeted as mineral fertilizers, and thus, the nitrogen utilization efficiency is poor. Animal manure can become a problem in terms of excessive use in areas of intensive agriculture with high numbers of livestock and too little available farmland. Fertilizing elements of organic fertilizers are mostly bound in carbonaceous reduced compounds. If these are already partially oxidized as in the compost, the fertilizing minerals are adsorbed on the degradation products (humic acids) etc. Thus, they exhibit a slow-release effect and are usually less rapidly leached compared to mineral fertilizers. In the case of phosphorus in particular, reuse of excreta is one known method to recover phosphorus to mitigate the looming shortage (also known as "peak phosphorus") of economical mined phosphorus. Mined phosphorus is a limited resource that is being used up for fertilizer production at an ever-increasing rate, which is threatening worldwide food security. Therefore, phosphorus from excreta-based fertilizers is an interesting alternative to fertilizers containing mined phosphate ore. Urine is primarily composed of water and urea. It contains large quantities of nitrogen (N) (mostly as urea), as well as reasonable quantities of dissolved potassium. The nutrient concentrations in urine vary with diet. In particular, nitrogen content in urine is related to quantity of protein in the diet: A high protein diet results in high urea levels in urine. Urine's eight main ionic species (> 0.1 meq L−1) are cations Na, K, NH4, Ca and the anions, Cl, SO4, PO4 and HCO3. Urine typically contains 70% of the nitrogen and more than half the potassium found in sewage, while making up less than 1% of the overall volume. Urine fertilizer is usually applied diluted with water because undiluted urine can chemically burn the leaves or roots of some plants, particularly if the soil moisture content is low. The dilution also helps to reduce odor development following application. Applying urine as fertilizer has been called "closing the cycle of agricultural nutrient flows" or ecological sanitation or ecosan. When diluted with water (at a 1:5 ratio for container-grown annual crops with fresh growing medium each season or a 1:8 ratio for more general use), it can be applied directly to soil as a fertilizer. The fertilization effect of urine has been found to be comparable to that of commercial nitrogen fertilizers.