BIOSOLIDS
Biosolid byproducts are considered as wastes in Ireland and USA, so their application as soil amendment will be comparatively economical in these countries (Meyer et al., 2001). Surface runoff and leaching from soil surface leads to loss of several organic and inorganic nutrients where land applications are followed by periodic rainfall (Gottschall et al., 2012). Application of biosolids on land is an important way leading to entering of contaminants into the environment as shown in many previous studies (Smith, 2009).
Biosolids provide a lot of benefits to soil application and they are only disposed off in the soil. The entry of biosolids into the human food chains and risks related to them was insignificant due to minimum uptake by plants when they are applied on land. As phosphorous resources are depleting, the land application of biosolids are also becoming progr essively more essential feature of sustainable nutrient management (Steen, 1998).
BONE MEAL
Meal bone meal (MBM) is an organic and essential source of important nutrients which are required for optimum growth and development of crop plants. It contains high amounts of nutrients such as nitrogen and phosphorous in the ratio of 8% and 5% respectively which makes it a significant source of nutrients for different crop plants. Bone meal reduces the requirement of crops for mineral fertilizers and it is also a fact that MBM has positive indirect influence on the environment. It also provides a source for the safe disposal of a large quantity of wastes from meat processing industries (Chen et al., 2011). They also provide an exceptional source of important elements and metals required for better grow'th of crops and plants when they are treated to required standards on grasslands and arable soils (Meyer et al.,
2001).Physical and chemical properties of soil can also be improved by bone meal amendment (Salomonsson et al., 1995). The potato quality can also be enhanced by soil amendment with MBM due to reduction in the risks of attack of potato scab and by also a limited population of parasitic nematodes (Fredriksson et al., 1998). Therefore, meat and bone meal has been allowed to be used as organic fertilizer for all crops except grasslands. These grasslands are used for grazing or mowing. Because the bone meal is organically bound, and it must be transformed to the inorganic form of nitrogen to make it available for the use of plants. Bone meal has low carbon to nitrogen ratio which favors faster mineralization of nitrogen than most of the other natural fertilizers (Tammeorg et al., 2012). Carbon to nitrogen ratio is used for approximation of organic matter quality in the soil to estimate nitrification and decomposition processes. As bone meal consists of adequate amounts of nitrogen, phosphorous, and calcium which makes it an attractive organic fertilizer to be used for different crops(Van et al., 2009).
COTTONSEED MEAL
The product, after removing oil from the cottonseed, is known as cottonseed meal. Cottonseed meal is absolute fertilizer which consists of 7-2.5-1.5% N-P-K respectively. It is byproduct of many cotton species like Gossypium hirsutum and Gossypium herbaceum. About 4-5 pounds of cottonseed meal should be applied for optimum productivity of flowers and vegetables per hundred square feet of land area and it should be applied into the soil before planting of crops (Roy et al., 2012). Soil texture can be improved by cottonseed meal and it also improves the growth of plants and soil health by providing humic acid to soil (Tenuta and Lazarovits, 2004). Hence, cottonseed meal aids in improving water holding capacity of soil and also protects the soil from fast erosion. It also provides different substances to light and sandy soils and also loosens the crowded soil (Martin and Gershun, 1992). The concentration of potash, phosphorous, and other important nutrients can be increased in soil environs by application of cottonseed meal (Cooperband, 2002).
ALFALFA PELLETS
Alfalfa is an excellent source of nutrients and has high digestibility with a huge amount of biological yield. It is a perennial forage legume and provides a huge quantity of nitrogen in pasture system with a lot of economic benefits and is a good alternative source of nutrients to synthetic fertilizers application (Campillo et al., 2003). Alfalfa pellets are used as an animal feed because they are an excellent source of nitrogen which is up to 5% (Agehra and Wamcke, 2005).
They also contain high amounts of naturally occurring plant growth promoters such as trace minerals and triacontanol. These plant growth promoters help to improve growth and yield of several crops. An alfalfa green pellet consists of host of many micronutrients which are obligatory for gr owth of plants and are absent in many of predictable fertilizer products (Clark, 2008; Den et al., 2010). It enhances favorable environmental conditions for microbial activities, which results in healthy soil environs (Fageria and Baligar, 2008).
