Agriculture: Polymers In Crop Production Mulch And Fertilizer

It is known that to a great extent plant growth is determined by microclimates of the growing media. Under field condition such favorable microclimate can be created artificially by means of mulching including various plastic covering. Plastic mulch controls the dynamics of incoming and outgoing radiation and thus changes the soil thermal properties and conserves soil moisture by checking evapotranspiration losses. Several synthetic and natural polymers such as polyethylene (PE), poly(vinyl chloride), polybutylene, copolymers of ethylene with vinyl acetate, polyesters, starch, cellulose, and chitosan are being used to develop plastic mulch of varied properties. Synthetic polymers more specifically PE is being used extensively for mulching purpose. Off late in view of environmental concerns and problems related to disposal, various degradable plastics like oxo-degradable, biodegradable plastics are developed for crop mulching. To increase fertilizer use efficiency and reduce losses through leaching, run off, and volatilization, polymer-based controlled-release fertilizer formulations are developed. These fertilizer formulations ensure release of nutrients at very slow rate over prolong period of time to avoid losses of nutrients and optimum availability of nutrient around the rhizospheric zone. Different synthetic or natural polymers were reported to develop controlled-release fertilizer formulation either by encapsulating the core water soluble fertilizer or by chemically attachment to the functional groups of polymeric chain. The release of nutrients from these polymeric formulations occurs through membrane diffusion or hydrolysis and other degradation process.