Farm field fertilizers

The water running off this farm field contains many pesticides and fertilizers that can be harmful to ecosystems and human health. 

As a result of their geographical circumstances and these various historical developments, many estuaries appear to be among the most heavily loaded ecosystems in the world in terms of the amount of nitrogen and phosphorus received per unit area (Fig. 5). Even the farm fields of the American corn belt do not receive the fertilization common to many estuaries, and the nutrient inputs to natural terrestrial systems and fresh waters appear to be orders of magnitude lower. There are fewer data available on the inputs of metals and other pollutants to estuaries, but the evidence at hand suggests that the delivery of heavy metals to estuaries may equal or exceed that deposited from the atmosphere on heavily industrialized urban areas and exceed that deposited on rural terrestrial ecosystems by orders of magnitude (Fig. 6). 

Diffuse Sources Pollution that comes from a wide range of sources, not from a single source, is said to come from a diffuse source. (See Figure 9.7.) A heavy downpour can cause run-off from farm fields to enter rivers and lakes. This run-off often carries undesirable pollutants, including fecal matter, pesticides, and fertilizer compounds, such as nitrates and phosphates. 

Figure 7.20 Fertilizers applied to these farm fields typically contain large quantities of potassium, phosphorus, and nitrogen to mert the needs of growing plants. 

Secondary and Micronutrients in Fertilizers The great majority of farm fertilizers are produced, marketed, and appHed with regard only to the primary plant nutrient content. The natural supply of secondary and micronutrients in the majority of soils is usually sufficient for optimum growth of most principal crops. There are, however, many identified geographical areas and crop—soil combinations for which soil appHcation of secondary and/or micronutrient sources is beneficial or even essential. The fertilizer industry accepts the responsibiHty for providing these secondary and micronutrients, most often as an additive or adjunct to primary nutrient fertilizers. However, the source chemicals used to provide the secondary and micronutrient elements are usually procured from outside the fertilizer industry, for example from mineral processors. The responsibiHties of the fertilizer producer include procurement of an acceptable source material and incorporation in a manner that does not decrease the chemical or physical acceptabiHty of the fertilizer product and provides uniform appHcation of the added elements on the field. 

In the summer of 1972 in the Kuybyshev Collective Farm in the Krivoozersk Region, a field was fertilized with ammonia solution 14 days after treatment with polychlorpinen. Twenty-seven female collective farm workers went into the field on the following day (the 15th after treatment with polychlorpinen), and were immediately poisoned. Seven days later they were sent again to the same field, with the same result. 

On May 1-2, 1974, a field from the Zhdanov Collective Farm in the Krivoozersk Region was treated with polychlorpinen. On May 15-25, 57 female collective farm workers worked in this field with no complaints. From May 30-June 6 the field was fertilized with ammonium nitrate, and on June 8 it rained. When, on June 11, the same 57 women worked in this field again, by 2pm all developed acute gas poisoning (the concentration of polychlorpinen in the air over the field three days later was only 0.04 mg/m3). 

Agronomic and entomological practices. Plants of diverse cotton lines were grown In field plots during the years 1978-1982 on the Plant Science Farm at Mississippi State University. Plants were treated for boll weevils with Guthlon, and normal fertilizer, herbicide, and other cultural practices were applied. The field design was normally a randomized complete block with 4 replications. Plant material (terminals. 

---