Fertilizers application levels

Problems associated with excessive levels of nutrients and unwanted nuisance species have already been mentioned. There are cases in which intentional fertilization is used by aquaculturists in order to produce desirable types of natural food for the species under culture. Examples of this approach include inorganic fertilizer applications in ponds to promote phytoplankton and zooplankton blooms that provide food for young fish such as channel catfish, the development of algal mats through fertilization of milkfish ponds, and the use of organic fertilizers (from livestock and human excrement) in Chinese carp ponds to encourage the growth of phytoplankton, macrophytes, and benthic invertebrates. In the latter instance, various species of carp with different food habits are stocked to ensure that all of the types of natural foods produced as a result of fertilization are consumed. 

Virgin soil can be rich in nutrients but at levels that may not be optimal. The soil should therefore be tested for its nutrient content before planting seeds. Nutrients are depleted with repeated production of crops and hence it is important to monitor the concentration of nutrients in the soil and supplement them as required (Seiler 1986). In most third-world countries fertilizer application and irrigation are costly and, sometimes, impossible. 

In accordance with the type of crop protection procedure, the stages of the work had different cycle times. For herbicide application, the complete task was done in approximately 18 minutes, while, in the fertilizer application was finished in only 5 minutes. Samples collection allowed us to identify the Vibration Dose Value in RMS (RMS VDV), maximum peak level (Peak), and value of daily exposure (8-hour reference period) to WBV (A(8)). EMB-201A aircraft applying herbicide, (sample = 01 36 41, n = 5792), showed RMS VDV = 8,053 m/s and Peak = 141,490 m/s. Also applying herbicide, EMB-202 aircraft (sample = 01 31 40, n = 5493), showed RMS VDV = 11,098 m/s and Peak=96,774 m/s. Finally, EMB-202 aircraft applying fertilizer (sample = 01 17 11, n = 4624) showed RMS VDV = 9,470 m/s and Peak = 120,277 m/s. Figure 1 show data points corresponding to the combined axis (X, Y and Z) Vibration Total Value (RMS VTV) for these three situations respectively. 

The soil macronutrients, nitrogen (N), phosphorus (P), and potassium (K), are essential for crop growth, and the use of commercial N, P, and K fertilizers has contributed greatly to the increased yield of agricultural crops. However, excessive fertilizer applications can lead to environmental contamination, primarily of surface and ground waters.Ideally, fertilizer application should be adjusted to match the requirements for optimum crop production at each within-held location, because there can be high spatial variability in the N, P, and K levels found within helds. ° ° ... 

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