• Asian-Australasian Journal of Animal Sciences
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• v.24 no.12
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• pp.1699-1705
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• 2011

Magnesium ammonium phosphate (MAP) was recovered from swine wastewater and the feasibility of reutilizing it as a slowly-releasing fertilizer was evaluated. Maize growth was investigated with normal and high application rates of MAP and a fused super phosphate (FSP) fertilizer. A total of 5 treatments ($T_0$ = control, $T_1$ = MAP based on 30 kg P $ha^{-1}$, $T_2$ = FSP based on 30 kg P $ha^{-1}$+urea equivalent to nitrogen of MAP applied in $T_1$, $T_3$ = MAP based on 40 kg P $ha^{-1}$, $T_4$ = FSP based on 40 kg P $ha^{-1}$+urea equivalent to nitrogen of MAP applied in $T_3$) were arranged with 3 replications. In the case of height and circumference, significant differences were found between controls and treated maize plants (p<0.01). However, no statistical differences were found between MAP- and FSP-urea treated maize. Leaf area and green biomass yield were significantly (p<0.01) higher in the treated group than control. Leaf area was also found significantly higher (p<0.01) in the higher MAP- treated group (2,374 $cm^2$ $plant^{-1}$) than other treatments. $N_2O$ emission was found to be lower in MAP treated soil than that from FSP-urea treated soil, which might be due to the slow releasing pattern of MAP. It could be assumed from the results that MAP would be an eco-friendly sustainable fertilizer source for crop production.

• Korean Journal of Soil Science and Fertilizer
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• v.22 no.3
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• pp.215-220
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• 1989

For development of slow releaseing K-fertilizer using natural zeolite, two kinds of K adsorbed zeolite were made by ion exchange reaction in $K^+$ saturated aqueous solution. K-Zeolite was prepared by removing the excess salt after K adsorption on zeolite, however, NW. K-Zeolite was prepared only by K adsorption reaction without removing the excess salt. The adsorbed K on zeolite was not easily released, but continuously and slowly released from the surface of zeolite. By the results of application for tobacco cultivation, the K contents in soil treated with K-Zeolite and NW. K-Zeolite were lower than that of control (20kg/10a) at the early growth stage, but were higher at the late growth stage. Therefore, the results suggest that K adsorbed zeolite could be applied as a slow-releasing K fertilizer.

• Journal of Animal Science and Technology
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• v.51 no.3
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• pp.249-254
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• 2009

The effect of Mg supplement on the composting of swine manure and the formation of $MgNH_4PO_46H_2O$ (MAP) crystal during composting were examined. Mg source was added at a rate of 1.2 molar ratios to soluble phosphate ($PO_4$) level in swine manure. The temperature profiles and final compost qualities revealed that the Mg source addition didn't retard the decomposition of organic matters. As the added Mg reacted with $NH_4$ and $PO_4$ in manure, creating MAP crystal, the $NH_4$ level was reduced, and this was resulted in low nitrogen lose during the composting. The phosphate level was also decreased with the addition of Mg source, and hence the ratio of orthophosphate to total phosphate (OP/TP) in the final compost was lowered. Therefore, it was assured that supplement of Mg source into the composting materials could enhance the quality of compost by preserving nourishment and converting it into a slowly releasing fertilizer. X-Ray diffraction examination of the final compost showed that a distinct MAP crystal was formed during the composting, and the crystal mainly existed with the compost particle size less than 2.8 mm and over 2/3 of nourishment of the final compost was found in those particles.

• Korean Journal of Soil Science and Fertilizer
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• v.38 no.4
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• pp.211-217
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• 2005

Fresh hairy vetch (HV) as a green manure equivalent to $240kg\;N\;ha^{-1}$ were incorporated into soil at corn planting in 1997 and 1998 to clarify the effects on changes of nitrogen (N) content in soil and corn plant. The influences of HV for the N of soil and plant were compared with those of ammonium nitrate (AN) in terms of mineralization and microbial biomass. During early decomposition of HV residue, the content of $NO_3-N$ in HV plot was as much as 60-70% of that in AN plot in surface soil of 0-15 cm depth. In addition, soil microbial biomass N (SMBN) by HV residue was increased up to $10-20mg\;kg^{-1}$ more than that by AN. Some mineral N from HV seemed to be released slowly until late corn growth stage judging from high content of $NO_3-N$ in both corn stem at silking stage and soil at harvest. There were no difference of N accumulations in corn plant at silking stage between HV and AN plots in both 1997 and 1998. At harvesting stage, a total of plant N accumulation in HV plot in 1997 was 8% less than that in AN plot while in 1998 it was 19% more. It was concluded that fresh HV green manure equivalent to $240kg\;N\;ha^{-1}$ was good enough to substitute the same amount with chemical N fertilizer by slow releasing of mineral N from HV residue in soil.