Identification of anthropogenic parameters for a regional nitrogen balance model via field investigation of six ecosystems in China

Abstract

To evaluate the impact of human behavior (with regard food consumption, waste disposal and farming method) on nitrogen flow, a field investigation was conducted in six typical ecosystems in China. A number of parameters for regional nitrogen balance models were identified during the investigation. The results show that the average percapita daily protein intake is 107 g. While there is an insignificant difference in total protein intake among the different ecosystems, protein intake from all food groups, except for eggs, is significantly different (P B 0.05). Differences in diet, along with those in socio-economic conditions, reflect differences in the characteristics of the ecosystems. Regarding percapita annual potential nitrogen loading from human excrement, a considerable difference exists between the urban rich and the rural poor. In urban areas, approximately 1.02 kg N is returned to farmlands and 5.49 kg N is directly discharged into rivers. In rural regions, on the other hand, approximately 4.33 kg N is returned to farmlands and 1.60 kg N is directly discharged into rivers. Furthermore, urea and mixed fertilizers constitute the most common chemical fertilizers in the study area. Fertilizer diversification is practiced in a range of agricultural lands, paddyfields and irrigated plains. In the oasis and paddyfield agricultural systems, many of the agricultural by-products (e.g., straw) are burned or mixed with base-fertilizers and plowed into the soil. In irrigated agricultural systems, over 70% of agricultural byproducts are recycled as livestock feed. In most instances, livestock excrement is directly reduced in the pasturelands or reused in the fields as manure. Occasionally, as in the case of large-scale breeding, excrements are usually abandoned.

Exploring global nitrogen and phosphorus flows in urban wastes during the twentieth century

“…This agrees with literature for the U.K. [ Cathcart and Murray , ] and the general pattern of increasing household and retail food waste losses as incomes grow [ SIK/FAO , ]. The country average per capita protein consumption was directly applied to urban inhabitants, which is in agreement with observed small differences between rural and urban protein consumption [ Liu et al ., ; Liu , ; Qiao et al ., ; Shehu et al ., ].…”

Socioeconomic Driving Factors of Nitrogen Load from Food Consumption and Preventive Measures

“…Many studies on nitrogen loading have shown that excess nitrogen from human activities has threatened air and water quality, disrupted the health of terrestrial and aquatic ecosystems, and has generally been detrimental to global ecosystems (Rockström et al 2009). Many studies have clarified that human food consumption has a major impact on the environmental nitrogen load (Smil 1999(Smil , 2002Shindo et al 2003;Liu et al 2008Liu et al , 2009Liu et al , 2013Leach et al 2012).…”

Effect of reforestation on nitrogen and phosphorus dynamics in the catchment ecosystems of subtropical China: the example of the Hanjiang River basin

“…For this purpose, we initially investigated nitrogen (N) flow, largely in relation to food production and consumption, in different agricultural regions in China. We especially targeted the Changjiang River basin by using a database of county‐level agricultural statistics and field investigations 5–8. However, these examinations were limited to the use of inventory budget models to determine past and current issues rather than dynamic process models that would allow for prediction of future changes and scenarios for effective management and decision making at the catchment scale.…”