Improving the management of water and nitrogen fertiliser for agricultural profitability, water quality and reduced nitrous oxide emissions in China and Australia

Most of the planned activities and milestones outlined in the project proposal for the first year (of a four year project) have been achieved, and summarized as follows:

In China:
1. A comprehensive experimental and data collection protocol for the project was developed and distributed to all the project members.
2. Four experimental sites were selected, (a) irrigated maize system in the western part of the Inner Mongolia Autonomous Region (IMAR) in collaboration with AusAID project of Alxa League Environmental Rehabilitation and Management, and (b) three sites in Shanxi province; the northern site at Yuci in the Taiyuan Basin, the southern site at Yongji near the edge of the North China Plain and the Hongtong site which lies in between. Both Yuci and Yongji sites were extensively instrumented to measure all key water and N fluxes.
3. Farmer socio-economic survey, field experiments for quantifying efficiencies of irrigation and N fertiliser using 15N labelled urea, and collection of soil and plant samples for N dynamics have been completed.
4. Sophisticated instruments have been installed at Yuci and Yongji, including micrometeorological Eddy correlation facilities, automatic soil moisture instruments and automated chambers with gas chromatography (GC) for N2O (Yuci site), and microplots receiving fertiliser enriched with stable 15N isotope to trace the fate of fertiliser N.
5. First year comprehensive water and N balance measurements have been completed at Yuci, most of the collected soil and plant samples have been analysed.
6. Targeted farmers socio-economic survey was completed in Fengqiu county to study the reasons for low adoption rates of water saving techniques recommended in a recently completed ACIAR project. Based on the survey data and the data from this previous ACIAR project, a conceptual module of the economic component has been established for water and nutrient management model (WNMM).
7. Chinese Academy of Sciences has approved 3 million RMB (A$500,000) co-funding to support this project (Prof Zheng Xunhua of Atmospheric Institute of Physics) to establish a state of art auto-chamber system for N2O and NOx measurements at the Yongji site.
8. The Shanxi Agricultural Comprehensive Development Office (SACDO) has agreed to fund 750,000 RMB (A$125,000) to implement the research outcomes of the project by establishing demonstration farms in all three counties in Shanxi.

In Australia:

The Australian component of project is complementary to projects funded through the CRC-Greenhouse Accounting, Australian Greenhouse Office (AGO) and GRDC, and mainly focus on model development.
9. The GIS interface of the WNMM has been converted to ArcGIS 9.x from ArcView GIS 3.x. The new WNMM-GIS interface for ArcGIS 9.x will make the spatially-referenced WNMM independent of the limitations set up by ESRI. However, the old version is still usable if the users have ArcView GIS 3.x.
10. The WNMM has been significantly modified and improved for Australian conditions:
A new component for simulating the localised soil pH change due to urea hydrolysis near urea granules and animal urine patches was added.
New crop growth models have been added to WNMM, including; SUCROS, ManageWheat model (John Angus, CSIRO), IRRI Oryza 2000 (to simulate rice growth), the CERES crop growth model (to simulate wheat and maize growth) and GrassGro (to simulate pasture growth and grazing). The new WNMM is a versatile agro-ecosystem model.
Three additional N2O emission modules have been added to WNMM for predicting the N2O emissions from soils; DNDC, DAYCENT and FASSET.
The web-based version of WNMM is nearly completed. This version of WNMM will allow users to access WNMM through internet connection to setup inputs files, to conduct simulations on our WNMM server, and to get the simulation results in text report and chart format produced by R software (http://www.R-Project.org) on our server. It is expected that the single location version will be accessible, rather than the spatially distributed version.

11. Applications WNMM in Australia and overseas.
The WNMM was adopted by CRC-GA for simulating water and N dynamics, and N2O emissions, for rain-fed wheat in Victoria and Western Australia and irrigated pastures in Victoria; N dynamics and NH3 volatilisation for south Korea, and water and N dynamics for an irrigated maize and wheat system in the Yaqui valley, Mexico by scientists from Stanford University, and legume systems in China by scientist from the Institute of Soil Science, Chinese Academy of Sciences. Significant outcomes are:
At Rutherglen, Victoria, the WNMM was applied to simulate N2O emissions from a rain-fed wheat cropping system with different stubble management practices, conventional cultivation of burnt stubble and direct drill with stubble retained. Both measured and simulated results showed that the differences in N2O emissions between the stubble management were small and the main driver for N2O emissions is soil moisture rather than the availability of soil mineral N.
The calibrated WNMM was used to simulate N2O emissions using historic climate data from 1968 to 2004 and four climate change scenarios (A1FI, A2, B1 and B2) of IPCC from 1990 to 2100 for seven scenarios of N fertilizer applications at the Rutherglen site. It was found that there were huge variations of annual N2O emissions, ranging from 0.1 to 0.6 kg N ha-1year-1 during the past 37 years. The annual N2O emissions were significantly correlated to climatic variables: annual average of daily maximum air temperature, annual rainfall and the N fertilizer application rate. The emission factors are around 0.1% of applied N which is well below the IPCC defaults value of 1.25%.
The water and N fluxes were successfully simulated by WNMM for the irrigated grazing pasture system at Kyabram. Four gas modules, DNDC, DAYCENT, WNMM and FASSET, under WNMM framework were compared for N2O simulations. The simulations of N2O emissions using the simplest WNMM module were the most accurate.

12. Soil N dynamics in irrigated maize systems impacted on by N and stubble management at Griffith, NSW were studied. The field measurements of denitrification, mineral N content and recovery of 15N labelled urea from micro-plots with and without ammonium thiosulfate (urease inhibitor), were complemented with laboratory studies of denitrification and N2O flux. Only 64-68% of applied labelled fertiliser was recovered from the 15N microplots. Significantly more fertiliser N was recovered in the grain from the stubble incorporated treatment than the stubble burned treatment and there was greater recovery of fertiliser N in the soil at the end of the experiment in the stubble burned treatment. The N2O emissions were strongly correlated with N application rates between 0 and 300 kg N/ha, with significantly more N2O emissions in the stubble burnt treatment than that the stubble incorporated treatment. The emission factors are between 1.5 to 2.5% of applied N which is higher than the IPCC's default value in contrast to the rain-fed wheat system in Australia.

13. A prototype of a handheld-based agricultural decision support system has been developed for advising farmers about N fertiliser use for wheat cropping in Australia. The system is operated on a hand held computer with built in digital camera and wireless functions (wireless network or GPRS). The soil N availability has been found to be correlated to the shoot density at early stages or the ground vegetation fraction which can be calculated from the in-situ photos taken by the built-in digital camera. The wireless networks or GPRS is used to download the real time weather data to calculate the wheat growing stages using the simplified WNMM model. The concept and the developing protocol may be adoptable in the Northern China region to extend the agricultural research results by this ACIAR project to the farmers who are very keen to hear and to adopt BMPs for social, economic and environmental benefits.

Most of the milestones outlined in the project proposal for the second year (of this four year project) have been achieved, and are summarized as follows:

In China:
1. Field experiments on irrigated maize in the Inner Mongolia Autonomous Region (IMAR), in collaboration with the AusAid project "Alxa League Environmental Rehabilitation and Management" have been completed. Using a combination of field measurement, modelling and 15N tracer techniques we found that 25 to 40% of irrigation water, and 186 to 255 kg N ha-1 of nitrate, was leached below the root zone. It was estimated that 50-90% of applied N fertiliser was lost.
2. The water and N management model, WNMM, has been adapted for simulating water and N dynamics under maize cropping in IMAR. Best management practices for these systems have been identified on the basis of WNMM simulations.
3. Two years of field experiments on water and N dynamics, plant growth and yield have been completed on irrigated wheat and maize at Yongji and Hongtong (Shanxi Province). The data is being used for testing WNMM in these environments. The Yongji site is extensively instrumented, including an Eddy Covariance system for measuring evapotranspiration and CO2 fluxes and a wireless soil moisture monitoring system. The preliminary results indicate that in Shanxi 30 to 160 kg/ha N fertiliser can be saved without reducing maize yields, and the corresponding saving for wheat is 40 to 100 kg/ha. This translates to 120 to 640 RMB/ha cost saving (1A$=6RMB). Similarly, significant amounts of irrigation water can be saved without lowering yield.
4. Open path laser and micrometeorological systems were used for the first time at Yongji to measure NH3 losses from irrigated maize. Sprinkler irrigation improved water use efficiency and substantially reduced NH3 volatilisation.
5. An economic sub-model is being constructed and linked to WNMM, using data gathered from a previous ACIAR project (LWR1/1996/164) and new survey data from Fengqu county (Henan province). The combined model will be used to assess the trade-off between environmental and economic objectives, and to assess policy options for water and fertiliser management.
6. Three county-wide suveys in Yuci, Yongji and Hongtong, Shanxi Province have been completed. Soil, landuse and village maps have been digitised and most attribute database sets have been compiled. This information is needed for developing the county-scale WNMM model and decision support system. Landsat TM5 images for 2006 have been purchased to estimate crop biomass, leaf area index and N uptake to calibrate WNMM.
7. The Chinese Academy of Sciences has approved A$500,000 co-funding to establish a state-of-the-art auto-chamber system for N2O and NOx measurements at the Yongji site. The system will be ready in October 2007 for the start of the wheat season.
8. The University of Wollongong is building a more portable open path FTIR system, for simultaneously measuring NH3, N2O, CO2, CH4 and CO. The system will be ready to be deployed in the 2008 wheat and maize seasons at Yongji, as well as in wheat, pasture and sugarcane sites in Australia.
9. The Shanxi Agricultural Comprehensive Development Office has funded A$50,000 to assist the social and soil survey in 2007, and has agreed to further funding to support establishment of demonstration farms in Shanxi.

In Australia:
This project is complimentary to work funded through the CRC-Greenhouse Accounting, Australian Greenhouse Office (AGO) and GRDC, mainly focusing on model development, measurement methodology and fundamental N process studies.
10. The WNMM has been significantly modified for Australian conditions:
- The web-based version of WNMM has been completed.
- The phosphorus sub-routine for WNMM has been developed and tested using the site dataset from Yuci County and will be tested for irrigated pastures in Australia.
11. Applications of WNMM in Australia assisted by this ACIAR project include simulation of water and N dynamics, and N2O emissions, for rain-fed wheat in Victoria and Western Australia and irrigated pastures in Victoria for AGO programs, and simulation of N dynamics in NSW within the ACIAR project led by Dr Jeff Evans. Other international applications, in association with the ACIAR project, include simulating N dynamics and NH3 volatilisation in rice for South Korea; simulating water and N dynamics for irrigated maize and wheat in the Yaqui valley, Mexico, by Stanford University, and; simulating N and water in legume systems in China by the Chinese Academy of Sciences.
12. Based on the ACIAR project, an application to the DEST China Special Fund, 'Improving water and agri-environmental sustainability in the Murray-Darling Basin and the North China Plain' was successful ($108,000). Also an additional $120,000 from AGO to fund two open path lasers for NH3 measurement was awarded.