Nitrogen and phosphorus leaching losses from paddy fields with different water and nitrogen managements

Abstract

While many water-saving rice production techniques have been adopted in China, the environmental effects of these techniques require further investigation. This study aims to assess nitrogen (N) and phosphorus (P) leaching losses under real conditions in different water and N managements. Two water and three N treatments are conducted in the Taihu Lake region of China. Results show that the total N leaching losses during the rice season under flooding irrigation (FI) are 12.4, 9.31, and 7.17 kg ha -1 for farmers' fertilization practices (FFP), site-specific N management (SSNM), and controlled-release nitrogen fertilizer management (CRN), respectively. Under controlled irrigation (CI), the respective losses were 7.40, 5.86, and 3.79 kg ha -1 for the same management methods. The total P leaching losses during the rice season under FI were 0.939, 0.927, and 0.353 kg ha -1 for FFP, SSNM, and CRN, respectively. Under CI, the losses were 0.424, 0.433, and 0.279 kg ha -1 , respectively, for the same management methods. Ammonium and nitrate N accounted for 42.2-65.5% and 11.8-14.7% of the total nitrogen leaching losses under different water and N management methods, respectively. Due to significant decrease of volumes of percolation water and nitrogen and phosphorus concentrations in percolation water, N and P leaching losses were reduced in the CI treatment compared to the FI treatment under the same N management. The reduction of N input and application of controlled-release nitrogen fertilizer can reduce N and P leaching losses from paddy fields.

Modeling of Soil Water Regime and Water Balance in a Transplanted Rice Field Experiment with Reduced Irrigation

“…The mean age of the rice seedlings at transplanting was approximately 1 month. Rice seedlings were mechanically transplanted at a rate of about four seedlings per hill two days after the basal fertilizer application (i.e., 21 [27].…”

“…While in the Taihu Lake basin, water is not a limiting factor for the agricultural production, a worsening quality of surface waters and groundwater, due to increasing nitrogen and phosphorus surface runoff and leaching from agricultural lands [21,26], has become a serious problem. Increasing the WP by adopting the MSI method can reduce water and nutrient losses from TPR fields, compared to DSR fields.…”

Impact of Alternate Drought and Flooding Stress on Water Use, and Nitrogen and Phosphorus Losses in a Paddy Field

“…AWD irrigation can reduce unproductive losses of water due to lower percolation and evaporation. Previous studies have shown that AWD can reduce the N and P leaching by signifi cantly cutting the volume of percolating water compared with conventional fl ooding irrigation [9][10]. Controlled drainage can control the groundwater table effectively via the installation of a subsurface drain.…”

Nitrogen Losses in Paddy Field Drainage Modified by Different Water Level Regulations

“…Paddy field irrigation methods therefore pose a serious hazard to rural water environments. Therefore, controlled irrigation-drainage techniques have been implemented through regulation of the water levels in paddy fields [5][6][7]. Controlled irrigation-drainage increases water use efficiency through water level control while ensuring normal rice yields [8][9].…”