New Progress in Variety Improvement
                   of Chemical Fertilizers
                         By Hua Xin
1. Modification of ammonium carbonate
Shanghai  Research  Institute  of  Chemical  Industry   has
developed an additive  of  ammonium  carbonate  which  can
prevent scaling and evaporation. It has also developed the
chemical  dehydration  process.   Phosphate  and  potassic
compound fertilizers made from ammonium phosphate and some
2-valence metallic salts are added to ammonium  carbonate.
The process is now being disseminated nationwide  and  the
capacity has reached over 1 million t/a.  In  some  plants
mixed light rare earth compound fertilizers are  added  to
improve the stability and  utilization  rate  of  ammonium
carbonate. Long-lasting ammonium  carbonate  developed  by
Shenyang Research Institute  of  Applied  Ecology  of  the
Chinese Academy of Sciences can increase  the  utilization
rate of nitrogen in ammonium carbonate from  25%  to  35%,
extend the fertilizer effect duration from 35 days to 90 -
110 days, increase the crop yield by 11 - 13%  and  reduce
the storage loss from 20% to 2 - 5%.
2. Modification of urea
Coated urea developed by Guangzhou  Nitrogenous  Fertilizer
Plant can improve the utilization rate and  is  now  being
disseminated nationwide. The Soil and Fertilizer Institute
of the Chinese Academy of Agricultural  Sciences  and  the
  Phosphate  Compound  Fertilizer  Institute  of  Zhengzhou
University  have  jointly  developed  the  technology  for
production of urea coated  with  fused  calcium- magnesium
phosphate.  The  fertilizer  effect  is  higher  than  the
mixture of urea and fused calcium-magnesium  phosphate  by
simple blending. Urea hot-melted with calcium sulfate  can
improve the utilization rate of nitrogen and  have  better
agrochemical properties than conventional urea.   Shanghai
Research  Institute  of  Chemical  Industry  has  recently
developed the  urea  and  calcium  superphosphate  process
which can be used in renovation of  single  superphosphate
  plants  and  have  a  bright  prospect.   The   Chemistry
Department of Sichuan United University has developed  the
technology for producing granulated  compound  fertilizers
by blending phosphate powder with  urea  nitrate  or  urea
sulfate. Tests have proved that the  evaporation  loss  of
urea in soil is very little.
3. Development of specialized compound fertilizers
Since the 80's, compound fertilizers produced by  secondary
processing are being switched to specialized varieties.  1
746 compound  fertilizer  producers  have  got  production
licenses. The total capacity  is  around  20  million  t/a
(physical product), and  the  actual  output  in  1995  was
around 6.5 million t/a (physical product). The  technology
for production of compound fertilizers by the  granulation
process recently developed by Shanghai Research  Institute
of Chemical Industry  has  been  used  in  more  than  100
chemical fertilizer  producers.   The  extrusion  prilling
  technology  can  be  used  in  production   of   compound
fertilizers with ammonium carbonate as the matrix.   Small
production of compound fertilizers is made by  the  mixing
process. The output  of  liquid  compound  fertilizers  is
still small. Measures should therefore be taken to further
develop specialized compound fertilizers by  the  blending
process.
4.   Development  of  biological  and  functional  compound
fertilizers
The capacity of biological  compound  fertilizer  units  in
China is 15 000 - 35 000 t/a. Beijing Luyuan Biotechnology
Research Institute  has  developed  a  special  biological
compound fertilizer. 5 - 10% active fungus is added to N, P,
K, Mg, trace elements, rare earth and organic fertilizers.
It can enhance the granular  structure  of  soil,   reduce
scaling and improve moisture preservation.   It  can  also
help crops to have a good root development, a sound growth
, an early maturing and a quality improvement. The yield of
rice and wheat can be increased by  10  -   20%.   A  high
-efficiency  and  multi- functional  biological  fertilizer
  developed  by   Beijing   University   is   composed   of
microorganisms  of  different  types  and  with  different
functions, antibiotics needed by plants and various  trace
elements. It can increase the yield of grain crops by 10 -
30%. It can help crops to develop resistance  to  diseases
and have an early maturing. It causes no harm to  man  and
animal and  no  pollution  to  environment.   Large  scale
production  of  the  product  has  already  started.   The
Biological Lab Center of Beijing Forestry  University  has
developed a functional plant steady-state fertilizer.   It
can be applied to soil at the time when it  is  needed  by
plants, and the plant growth and development can always be
at the best state. It causes no pollution to soil and  has
an effect duration of 4 - 12  months.   Tests