Increasing water productivity, nitrogen economy, and grain yield of rice by water saving irrigation and fertilizer-N management

Coupled one-off alternate furrow irrigation with nitrogen topdressing at jointing optimizes soil nitrate-N distribution and wheat nitrogen productivity in dryland

The judicious management of water and nitrogen (N) is pivotal for augmenting crop productivity and N use efficiency, while also mitigating environmental concerns. With the advent of the High-Farmland Construction Program in China, one-off irrigation has become feasible for most dryland fields, presenting a novel opportunity to explore the synergistic strategies of water and N management. This study delves into the impact of one-off alternate furrow irrigation (AFI) and topdressing N fertilizer (TN) on soil nitrate-N distribution, and N productivity-including plant N accumulation, translocation, and allocation, and grain yield, protein content, N use efficiency of winter wheat (Triticum aestivum L.) in 2018-2019 and 2019-2020. Experimental treatments administered at the jointing stage comprised of two irrigation methods-every (EFI) and alternative (AFI) furrow irrigation at 75 mm, and two topdressing N rates-0 (NTN) and 60 (TN) kg N ha-1. Additionally, a conventional local farmer practice featuring no irrigation and no topdressing N (NINTN) was served as control. Compared to NINTN, EFINTN substantially increased aboveground N accumulation, grain yield, and protein yield, albeit with a reduction in grain protein content by 8.1%-10.6%. AFI, in turn, led to higher nitrate-N accumulation in the 60-160 cm soil depth at booting and anthesis, but diminished levels at maturity, resulting in a significant surge in N accumulation from anthesis to maturity and its contribution to grain, N fertilizer partial factor productivity (PFPN), and N uptake efficiency (NUPE), thereby promoting grain yield by 9.9% and preserving grain protein content. Likewise, TN enhanced soil nitrate-N at key growth stages, reflected in marked improvements in N accumulation both from booting to anthesis and from anthesis to maturity, as well as in grain yield, protein content, and protein yield. The combination of AFI and TN (AFITN) yielded the highest grain yield, protein content, with PFPN, NUPE, and N internal efficiency outstripping those of EFINTN, but not AFINTN. In essence, one-off AFI coupled with TN at the jointing stage is a promising strategy for optimizing soil nitrate-N and enhancing wheat N productivity in dryland where one-off irrigation is assured.

The effects of climate extreme events on selected food crop yields in Sub-Saharan Africa

The agricultural sector is essential for economic growth. However, agricultural performance can be limited by factors such as climatic risks. This paper aims to analyse the effect of climate extreme events on selected food crop yield in sub-Saharan Africa (SSA). The study uses data from the Food and Agriculture Organisation (FAO) database for maize, rice, and sorghum yields. Also, we used data obtained from the International Disaster Database of the Centre for Research on the Epidemiology of Disasters (CRED) for floods and droughts over the period 1990-2020. The data were analysed based on the Fully Modified Ordinary Least Squares (FMOLS). The results showed that climate extreme events negatively affected maize, rice and sorghum yields. Also, the findings showed that floods and droughts in past years negatively influence current yields of maize, rice and sorghum. Moreover, agricultural labour force, fertilizer and financial development are the main transmission channels through which floods and droughts can affect maize, rice and sorghum yields. The study concludes by recommending that policies aimed at promoting climate change adaptation measures as well as agricultural insurance could make the agriculture sector more resilient to climate extreme events and in turn that could improve agricultural productivity and reduce food insecurity.

Spatial Analysis of the Vulnerability to Flooding in the Rural Context: The Case of the Emilia Romagna Region

The adversities of climate change represent a serious risk factor on both food production, rural territories and landscapes. In light of these irreversible trends, the process of adaptation of the rural territory is a necessary step, in order to increase its climate resilience. In this study, the vulnerability assessment was the tool used to evaluate the specific phenomenon of “flooding and backwatering” in the case study of Emilia Romagna region (Italy). The approach was based on the IPCC’s risk analysis methodology, populated by different layers regarding specifical proxies related to the adaptive capacity and the sensitivity of the territory to water stagnation, then we assessed with the normalization process of the different information levels. The aim of the research consisted in the realization of a regional map of the vulnerability to floods and backwaters, in order to rank the territory to this specific phenomenon. The final result could be useful both for the relationship with planning choices and for local-based actions in agricultural policies that in Italy are taken at regional level.

Exploration of water-nitrogen coupling effects in paddy field based on ORYZA (v3) model

BACKGROUND

Nitrogen and water are two major factors in rice production. Due to the lack of ample evidence and much uncertainty in field experiments, the coupling effects of water and nitrogen in paddy fields have remained debatable over recent years.

RESULTS

A fine-calibrated ORYZA (v3) model was applied to simulate rice growth and development under different nitrogen (N) rates and irrigation regimes for a double rice-cropping system in South China. We designed a numerical experiment of 504 treatments, consisting of seven nitrogen rates (0-300 kg ha^-1 ), eight irrigation thresholds (30-100%, presented as the percentage of saturated soil water content) and nine irrigation quotas (20-100 mm), and each treatment was simulated for 30 years. Yield varied greatly with different water-nitrogen conditions, particularly in the scenario of frequently alternate wetting and drying irrigation and low-N rates. The coupling effects had a negligible influence on water input and water loss, which were found to be sensitive only to the irrigation regime and rainfall distribution. Based on the results, the N fertilizer for early rice growing in the wet season is suggested as 150-200 kg ha^-1 , and 200-250 kg ha^-1 for late rice growing in the dry season. The irrigating threshold and irrigation quota for early rice are suggested as lower than 70% and 30-40 mm, respectively, and, for late rice, 70-80% and 40-60 mm.

CONCLUSION

Remarkable water-nitrogen coupling effects were found in the paddy field, and integrative water-nitrogen management strategies were suggested for both early rice and late rice in South China. © 2021 Society of Chemical Industry.

A Model of Evapotranspirative Irrigation to Manage the Various Water Levels in the System of Rice Intensification (SRI) and Its Effect on Crop and Water Productivities

Evapotranspirative irrigation is a simple idea in a watering field based on the actual evapotranspiration rate, by operating an automatic floating valve in the inlet without electric power to manage water levels. The current study introduces a model of evapotranspirative irrigation and its application under different water levels. The objectives were (1) to evaluate the performances of evapotranspirative irrigation under various irrigation regimes, and to (2) to observe crop and water productivities of the system of rice intensification (SRI) as affected by different types of irrigation. The experiment was performed during one rice planting season, starting from July to November 2020, with three irrigation regimes, i.e., continuous flooded (CFI), moderate flooded (MFI) and water-saving irrigation (WSI). Good performance of the system was achieved; low root mean square error (RMSE) was indicated between observed water level and the set point in all irrigation regimes. Developing a better drainage system can improve the system. Among the regimes, the WSI regime was most effective in water use. It was able to increase water productivity by up to 14.5% while maintaining the crop yield. In addition, it has the highest water-use efficiency index. The index was 34% and 52% higher than those of the MFI and CFI regimes, respectively. Accordingly, the evapotranspirative irrigation was effective in controlling various water levels, and we recommend the system implemented at the field levels.

Water Allocation and Integrative Management of Precision Irrigation: A Systematic Review

Precision irrigation, defined as an efficient water allocation technique characterized by the optimal management and best collaboration of various factors of the irrigation process, attracts considerable attention in agricultural production and crop cultivation. This paper reviews the latest research developments in water allocation mechanism and integrative management effectiveness of precision irrigation, and highlights how irrigation water allocation and integrative management contribute to the high-efficiency performance of precision irrigation techniques; the irrigation models, irrigation infrastructure, and management strategies currently being used are emphasized. Thereafter, the future development prospects in water allocation and integrative management could be systematically analyzed and subsequently explored. Some frontier techniques such as data-oriented irrigation management, performance-proven water allocation, and cloud-based irrigation control are among the critical technologies capable of building a sustainable, integrative, and evolutionary irrigation system while providing the higher quality and efficiency needed for a full application of precision irrigation. This review could be used as an effective reference to study the complicated correlations between precision irrigation and its constructive influences in different environmental conditions, and to facilitate the practical promotion of irrigation productivity with higher accuracy and increased reliability of returns.