The paper "Human Urine: A Possible Alternative in Organic Farming" is an outstanding example of an essay on environmental studies. Organic farming and its related practices have become the healthier option to prevent the contamination of soil, groundwater and farm produce with inorganic chemicals and pesticide residue that harm the environment and human beings (Karak and Bhattacharyya, 2011). Human urine is one type of waste that some scientists have studied to be a good organic fertilizer because of its organic chemical constituents that may aid in plant growth. This paper aims to establish that plants treated with diluted human urine are more robust compared to untreated plants, and plants treated with concentrated human urine are less likely to survive.
Plant Nutrition and Human Urine
Plants need three primary nutrients, namely: nitrogen (N), phosphorus, (P) and potassium (K) and are needed by plants in large amounts. These nutrients are not readily available in the soil, thus requiring applications of fertilizers to be able to help the plants survive. They also need minerals such as calcium (Ca), magnesium (Mg) and sulfur (S) but they are already present substantially in the soil and external application is not significantly necessary (ncagr.gov, n.d.).
Human urine, as waste from biological metabolism, contains both organic and inorganic chemicals of which the composition is similar to the nutrients needed by plants to grow. On average, adult humans excrete about 1.5 liters of urine every day. It is acidic in nature (pH 6.0) and is pale yellow in color. Its main component is water, approximately 95% and the remaining are the chemical constituents. Nitrogen is the main organic constituent in urine, which is derived from urea, ammonia and other nitrogen-containing organic substances and is about 19 grams per liter (g/L); while sodium chloride is the main inorganic salt which is about 8.3 g/L of urine (Rastogi, 2004). Given this composition, it can be clearly seen that human urine is a potent organic fertilizer.
Human Urine as Fertilizer
Nutrient deficiency and excess both pose risks to plant survival. Nitrogen is an important building block in photosynthesis, and its deficiency greatly affects the entire plant metabolism, from vegetative to reproductive stage. Excess of N, on the other hand, makes the plant more receptive to pests and weakens the stem because of excessive growth. Mineral salts, including sodium chloride, affect the salinity of the soil. Human urine has these mineral salts, thus, its effect on plants have to be considered as well. Excessive salinity decreases the plants’ capacity to take up N from the soil, consequently affecting photosynthesis and respiration (International Rice Research Institute [IRRI], n.d.).
Kirchmann and Pettersson (1995) evaluated the efficiency of human urine from which about 90% of the N in the urine sample was from ammonium bicarbonate and phosphorus was in its phosphate form. The study was able to establish the efficiency of urine to provide P to the plant, but not in the case of N. On the other hand, a study in South Africa was able to establish human urine as a good source of N for salinity-resistant crops like beetroot, tomato, and maize-based on improved root growth and increased dry matter. The results also showed that the application of human urine increases salinity thus providing a limitation to crops sensitive to saline conditions (Mnkeni, et al., 2008).
Proper application of urine is important to be able to achieve optimum amounts of nutrients and minimize the harmful effects of the acidity and salinity of concentrated urine (mtu.edu, n.d.). Jonsson et al (2004) have come up with possible guidelines on the use of excretions in plant cultivation. Data from different studies have established optimum formulations that would result in favorable plant growth, together with the frequency and dosage of the urine solutions that should be applied. Approximately, urine can be applied in amounts equivalent to 3-7 grams N/L; however, if there is yet no established amount of urine to be used, an estimated 6 liters for every square meter of the plant should be the maximum amount that can be applied. Otherwise, the toxic effects of human urine will start to become evident and affect plant growth.
Studies on human urine have shown its vital use as an alternative organic fertilizer as long as the correct amount of nitrogen must be present to be able to avoid the effects of excessive nitrogen and salts in the soil. The experiment to be conducted will be able to prove the established data from the literature and confirm that human urine can be indeed used as a plant fertilizer, and consequently be fully integrated as an agricultural practice.