Many technologies have been implied to boost up phosphorus (P) solubility such as use of P solubilizing microorganisms or use of organic acids. But little attention has been given to the use of organic polymer to enhance the P availability. Organic polymer can be used to develop phosphatic fertilizer that releases phosphorus (P) slowly. The organic polymer (complex organic compounds) absorbs water more efficiently and keeps the P in available form. The organic polymer can hold water many times of its weight and prolong the availability of P to plant roots. Phosphatic fertilizers with organic polymers are usually termed as slow releasing fertilizer because these fertilizers provide P to plants at slower rate but regularly. Therefore, now researchers are focusing on the use of polymer for DAP (diammonium phosphate) coating to prolong the availability of P in soil to replenish the pool of P to meet the plant requirements. Controlled-release fertilizers are being developed to improve nutrient use efficiency while reducing environmental hazards.
Controlled-Release Fertilizers:
It has also been reported that greater fruit yield was obtained using controlled-release fertilizers compared with water soluble fertilizers. This type of fertilizer can provide many benefits to agriculture, such as higher fertilizer use efficiency, reduced nutrient losses via fixation, leaching and denitrification and reduction of soil chemical processes that decrease the availability of nutrients, such as the fixation of P. Therefore coating of commercial DAP with organic polymer could be effective to prolog the availability of phosphorus to plants in soil.
Experiment at Coated DAP:
To investigate the efficiency of polymer coated DAP, field trial was conducted at research area of Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad. Different rates of organic polymer coated DAP (100, 75 and 50%) were applied in comparison with uncoated DAP. Data regarding plant height, number of tillers m-2, 1000-grain weight, grain yield and total grain yield were collected. Results of the study obtained after statistical analysis are summarized as under.
Results for Coated DAP:
Results of study indicated that wheat crop responded positively to the application of polymer coated DAP as compared to uncoated DAP and control (no P was applied). Application of polymer coated DAP improved the growth, yield and nutritional aspects of crop. 100% polymer coated DAP was found to be superior in most of the yield and growth parameters. Because polymer coating on DAP converted it into more available form for a longer period as it slowed down the release of P. Overall experiment results suggested that polymer coated DAP as P source significantly increased most of the growth and yield parameters. Polymer coated DAP has following benefits over uncoated DAP.
Polymer coated DAP:
- Increased nutrients uptake and hence their use efficiency.
- Performed better than uncoated DAP.
- Reduction in soil fixation of P that resulted in more availability of P in soil.
- Released the nutrients slowly and made it available throughout the growth period.
- Reduced the fertilizer application rate due to higher uptake compared to uncoated.
References:
- Murphy, L and L. Sanders. 2007. Improving N and P efficiency with polymer technology. Ind. CCA Conf. Pro. 1-13.
- NFDC. 1997. Fertilizer Recommendations for Crops. pp. 33-46. In. “Fertilizer Recommendations in Pakistan (a pocket guide for extension workers)”. National Fertilizer Development Center, Islamabad, Pakistan
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