Place: Research Lab of
Fertilizer and Balanced Fertilization, Department of Plant Nutrition, South China Agricultural University, Guangzhou 510642,
Title of the Project: Improving water
and fertilizer use efficiency in lowland rice production system by utilization of different ground cover rice production systems
(GCRPS) with attention to emissions of CH4, N2O and NH3
Supported by: National Nature Science Foundation of China (NSFC) and German Research Foundation (DFG)
Today, conventional lowland rice production systems, in general,
are characterized by high inputs of water and nitrogen fertilizer. Apparently, high emissions of CH4, N2O
and NH3 are inevitably linked to this type of rice production. It was not before recently, that successful alternative
approaches have been suggested. In the scope of the so-called Ground Cover Rice Production System (GCRPS), soil is irrigated
to approximately 70-90% water holding capacity. Thereafter, for reduction of evaporation, the soil is covered by covering
material, such as plastic film, paper or plant mulch. However, no reliable data on water and nitrogen fertilizer use efficiency
and on trace gas emissions are available for these systems. The experiments are being conducted in three different climatic
zones of China (Beijing, Nanjing and Guangzhou). The main objective of the experiment is on improving the water use efficiency
and nitrogen use efficiency (15N and difference method), and studies on emissions of CH4, N2O
and NH3 gases.
A field experiment was conducted in year 2001 at the
research farm of South China Agricultural University, Guangzhou, P.R. China (23 0N latitude; 113.4 0E
longitude). The treatments were paddy control (low lands); plastic mulch, straw mulch and bare soil (upland situation for
the later 3 treatments). Each treatment except control, received a total N of 225 kg ha-1. Rice variety Fenghua
Zhan was transplanted on August 10, 2001 at a spacing of 25x15 cm2. The harvesting of rice was done on November
12, 2001 for normal paddy and on December 14, 2001 for upland rice. The experimental design used was completely randomized
block with three replications. Size of the individual plot was 12x6 m2 for N1 (N-fertilized treatments). Additionally
to the three blocks of the main experiment, one block without nitrogen fertilizer application was set up with size of the
individual plots as 3 x 4 m2, for calculation of N uptake by difference method. Flooded conditions were maintained
in paddy control plots throughout the growing season.
Highest grain yield was observed in paddy control,
which was significantly higher to all the other treatments. Plastic mulch and straw mulch did not differ significantly with
respect to grain yield, but both produced significantly higher grain over bare soil. Again the highest grain yield was found
in paddy control, being at par to straw mulch and significantly greater to plastic mulch and bare soil under control (no nitrogen)
situation. The grain in paddy control has highest N concentration and N uptake, being significantly higher to other treatments.
As regards nitrogen use efficiency (NUE) and nitrogen fertilizer use efficiency (NfUE), significantly greater values were
recorded in paddy control in comparison to all the other three treatments. Bare soil treatment recorded significantly lower
figures for above two parameters as compared to other treatments. The NfUE values for rice biomass reduced significantly in
the order of plastic mulch to straw mulch and then straw mulch to bare soil. The highest amount of water was consumed in paddy
control treatment, followed by bare soil, straw mulch and plastic mulch. The plastic mulch was greatly helpful in reducing
the evaporation rate; hence, lowest water was consumed in plastic mulch treatment.
Under the commonwealth Academic Staff Fellowship 2008 and visited Newcastle University, United Kingdom
during 1st February 2009 to 31st July 2009 to conduct advanced study/ research on Organic Agriculture.