scholarly journals Crop Structure Changes Altered the Cropland Nitrogen Balance between 2005 and 2015 on the Sanjiang Plain, China

2018 ◽  
Vol 10 (11) ◽  
pp. 4011 ◽  
Author(s):  
Chunxia Yang ◽  
Hua Zheng ◽  
Binbin Huang ◽  
Ruonan Li ◽  
Zhiyun Ouyang ◽  
...  
Keyword(s):  
Soil Fertility ◽  
Nitrogen Balance ◽  
Agricultural Development ◽  
Driving Forces ◽  
Sanjiang Plain ◽  
N Balance ◽  
The Sanjiang Plain ◽  
Use Efficiency ◽  
The Impact ◽  
N Use

Nitrogen (N) budgets have been computed in many countries at various scales to improve understanding of N-balance characteristics and to assess the environmental pollution risks of applying chemical fertilizer N. However, dynamic characteristics, driving forces, and potential soil fertility consequences related to cropland N balance have seldom been discussed, especially in regions with highly fertile soils and low N-use intensities. This study investigated the temporal and spatial characteristics of N balance, and the impact of agricultural development on the agro-ecosystems of the Sanjiang Plain, one of the largest producers of commodity food grains in China. County-level agricultural statistics at five-year intervals were used to calculate agricultural N balances, N surplus intensity, and N-use efficiency between 2005 and 2015. Agricultural development has brought about continual increases in cultivated land area, consumption of chemical fertilizers, and nitrogen use efficiency (NUE). Nitrogen surplus intensity decreased from 65.0 kg/ha in 2005 to 43.5 kg/ha in 2010, and to 22.2 kg/ha in 2015. However, NUE was >90% in 13 counties in 2015, and in 11 counties in 2010. In contrast, only 5 counties had NUE above 90% in 2005, which indicates that N from the soil was used by crops and soil fertility was gradually decreasing. The percentage change of crop area, namely, the increase in maize area percentage, contributed significantly to the increases in NUE. A judicious management of fertilizers that meets the nutrient needs of the crops and ensures agricultural sustainability on the Sanjiang Plain is therefore essential. The findings of this study emphasize the importance of assessing the impact of crop structure adjustment on soil fertility and nitrogen balance during agricultural development.

scholarly journals Optimization of irrigation water use efficiency evaluation indicators based on DPSIR-ISD model

2019 ◽  
Vol 20 (1) ◽  
pp. 83-94 ◽  
Author(s):  
Liu Dong ◽  
Zhou Lihui ◽  
Li Heng ◽  
Fu Qiang ◽  
Li Mo ◽  
...  
Keyword(s):  
Water Use Efficiency ◽  
Water Use ◽  
Irrigation Water ◽  
Sanjiang Plain ◽  
Irrigation Water Use Efficiency ◽  
The Sanjiang Plain ◽  
The Sustainable Development ◽  
Irrigation Water Use ◽  
Use Efficiency ◽  
Agricultural Water Resources

Abstract The evaluation of irrigation water efficiency plays an important role in the efficient use of agricultural water resources and the sustainable development of agriculture. In order to make the evaluation of irrigation water use efficiency indicators more comprehensive and scientific, this paper constructs a new optimal model of evaluation indicators. By combining the Driver-Pressure-State-Impact-Response (DPSIR) model with the Information Significance Difference (ISD) evaluation indicators model, a novel DPSIR-ISD evaluation indicators combination model was constructed. Ten riverside irrigation areas in the Sanjiang Plain of northeastern China were selected for analysis. The results show that the DPSIR-ISD model was used to reduce the number of indicators from 44 to 14; these 14 indicators reflected 91.88% of the original information. The DPSIR-ISD method proposed in this paper takes into account the completeness and simplicity of the indicators system, and is more in line with the actual situation in the field. These results can provide a simpler and more convenient system for optimizing indicators for the study of evaluation indicators used to analyze irrigation water use efficiency.

scholarly journals The impact of long-term agricultural development on the wetlands landscape pattern in Sanjiang Plain

2012 ◽  
Vol 13 ◽  
pp. 1922-1932 ◽  
Author(s):  
Y.M. Xu ◽  
Y. Li ◽  
W. Ouyang ◽  
F.H. Hao ◽  
Z.L. Ding ◽  
...  
Keyword(s):  
Landscape Pattern ◽  
Agricultural Development ◽  
Sanjiang Plain ◽  
The Impact

scholarly journals Impacts of Intensified Agriculture Developments on Marsh Wetlands

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Zhaoqing Luan ◽  
Demin Zhou
Keyword(s):  
Agricultural Development ◽  
Agricultural Landscape ◽  
Nature Reserve ◽  
Spatiotemporal Analysis ◽  
Sanjiang Plain ◽  
Natural Marsh ◽  
The Sanjiang Plain ◽  
Wetland Ecosystems ◽  
The Past ◽  
Remote Sensing Techniques

A spatiotemporal analysis on the changes in the marsh landscape in the Honghe National Nature Reserve, a Ramsar reserve, and the surrounding farms in the core area of the Sanjiang Plain during the past 30 years was conducted by integrating field survey work with remote sensing techniques. The results indicated that intensified agricultural development had transformed a unique natural marsh landscape into an agricultural landscape during the past 30 years. Ninety percent of the natural marsh wetlands have been lost, and the areas of the other natural landscapes have decreased very rapidly. Most dry farmland had been replaced by paddy fields during the progressive change of the natural landscape to a farm landscape. Attempts of current Chinese institutions in preserving natural wetlands have achieved limited success. Few marsh wetlands have remained healthy, even after the establishment of the nature reserve. Their ecological qualities have been declining in response to the increasing threats to the remaining wetland habitats. Irrigation projects play a key role in such threats. Therefore, the sustainability of the natural wetland ecosystems is being threatened by increased regional agricultural development which reduced the number of wetland ecotypes and damaged the ecological quality.

scholarly journals Regulatory effect of phosphorus and nitrogen on nodulation and plant performance of leguminous shrubs

AoB Plants ◽  
2019 ◽  
Author(s):  
M A Míguez-Montero ◽  
A Valentine ◽  
M A Pérez-Fernández
Keyword(s):  
N Use Efficiency ◽  
P Availability ◽  
Physiological Basis ◽  
P Use Efficiency ◽  
Key Species ◽  
Use Efficiency ◽  
Inoculation Treatment ◽  
The Impact ◽  
P Supply ◽  
N Use

Abstract The impact of phosphorus (P) nutrition on plant growth, symbiotic N2 fixation, and phosphorus and nitrogen use and their assimilation was investigated in four leguminous plants of the genus Cytisus. Plants inoculated with Rhizobium strains isolated from plants of the four species growing in the wild were crop under controlled conditions in soils with either low P (5 µM) or high P (500 µM). The experiment was replicated in the presence and absence of plant irrigation to test for the effects of drought stress of inoculated and non-inoculated plants under the two P levels of fertilization. P-low treatments increased nodule production while plant biomass and shoot and root P and N contents were maximum at sufficient P. The reduction of P in the soil clearly induced biological nitrogen fixation and greater phosphorus and nitrogen uptake efficiencies, as shown by the total N and P accumulated in plants. Similarly, distinct tolerances to drought support this idea. Cytisus balansae had the lowest tolerance to water scarcity. Cytisus multiflorus and Cytisus scoparius were the most resistant species to drought, with this resistance enhanced in the inoculated plants. In the four species, the inoculation treatment clearly enhanced N-use efficiency, whereas P-use efficiency was greater in the non-inoculated plants in the irrigated treatment. With a P-induced demand for N, the plants nodulated prolifically and increased N supply from biological fixation. The physiological basis for N2-fixing C. scoparius and C. striatus maintaining growth at low P supply and responding to greater P supply is through balanced acquisition of P and N for plant demand. Native shrubby legumes are key species in natural ecosystems due to their capability to increase the net N budget in plants and soils and because they modulate the phosphorus availability. Four legumes in the genus Cytisus either native to or commonly represented in the Iberian Peninsula proved to be able shift their N use depending on the soil P availability and on the interactions established with their Bradyrhizobium symbionts. In the four species the inoculation treatment clearly enhanced N-use efficiency and drought tolerance, whereas P-use efficiency was greater in the non-inoculated plants in the irrigated treatment.

Productivity and nitrogen use of maize as affected by in situ and ex situ green manuring in major and minor seasons of tropical Asia

2009 ◽  
Vol 57 (3) ◽  
pp. 285-296 ◽  
Author(s):  
U. Sangakkara ◽  
P. Stamp
Keyword(s):  
Seed Yield ◽  
N Use Efficiency ◽  
Ex Situ ◽  
Green Manures ◽  
Smallholder Farming ◽  
Green Manuring ◽  
Use Efficiency ◽  
The Impact ◽  
N Use

Green manuring is considered an important agronomic practice for smallholder farming systems in the tropics. Different species of legumes and non-legumes are applied either as ex situ or in situ green manures. Thus a field study conducted under rainfed conditions in Sri Lanka compared the effect of in situ and ex situ green manuring using two popular green manures ( Crotolaria juncea — a legume and Tithonia diversifolia — a non-legume) on the growth, seed yield and N use pattern of maize ( Zea mays ), the most popular upland cereal in the Asian tropics, grown with high and low N rates, in the two seasons that correspond to the monsoonal rains. In situ green manuring, especially with crotolaria, increased the growth, seed yield and N use efficiency of maize when compared to the ex situ addition of similar quantities of the green manure. The impact was also greater in the minor season, when the crop was subjected to moisture stress conditions. The benefits of in situ green manuring with tithonia were lower than those due to crotolaria. In situ green manuring with tithonia also led to a greater increase in growth, seed yield and N use efficiency in maize compared to ex situ green manuring with this species. The green manures, especially in situ application, also increased the benefits of enhanced rates of N fertilizer to the crops in both seasons, with greater use efficiency in the major season. The study showed the benefits of green manuring (both in and ex situ ) for obtaining higher yields of maize in the growing seasons of the Asian tropics, especially the in situ application of legume species.

scholarly journals Optimizing Feature Selection of Individual Crop Types for Improved Crop Mapping

2020 ◽  
Vol 12 (1) ◽  
pp. 162 ◽  
Author(s):  
Leikun Yin ◽  
Nanshan You ◽  
Geli Zhang ◽  
Jianxi Huang ◽  
Jinwei Dong
Keyword(s):  
Feature Selection ◽  
Agricultural Development ◽  
Development Planning ◽  
Sanjiang Plain ◽  
The Sanjiang Plain ◽  
Regional Food ◽  
Probability Maps ◽  
Medium Resolution ◽  
Crop Mapping ◽  
Crop Types

Accurate crop planting area information is of significance for understanding regional food security and agricultural development planning. While increasing numbers of medium resolution satellite imagery and improved classification algorithms have been used for crop mapping, limited efforts have been made in feature selection, despite its vital impacts on crop classification. Furthermore, different crop types have their unique spectral and phenology characteristics; however, the different features of individual crop types have not been well understood and considered in previous studies of crop mapping. Here, we examined an optimized strategy to integrate specific features of individual crop types for mapping an improved crop type layer in the Sanjiang Plain, a new food bowl in China, by using all Sentinel-2 time series images in 2018. First, an automatic spectro-temporal feature selection (ASTFS) method was used to obtain optimal features for individual crops (rice, corn, and soybean), including sorting all features by the global separability indices for each crop and removing redundant features by accuracy changes when adding new features. Second, the ASTFS-based optimized feature sets for individual crops were used to produce three crop probability maps with the Random Forest classifier. Third, the probability maps were then composited into the final crop layer by considering the probability of each crop at every pixel. The resultant crop layer showed an improved accuracy (overall accuracy = 93.94%, Kappa coefficient = 0.92) than the other classifications without such a feature optimizing process. Our results indicate the potential of the ASTFS method for improving regional crop mapping.

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