Doktorarbeit: Optimization of Nutrient and Carbon Management of Agricultural Land in the Peri-Urban Region of Beijing with Intensive Animal Husbandry

Optimization of Nutrient and Carbon Management of Agricultural Land in the Peri-Urban Region of Beijing with Intensive Animal Husbandry

AGRARIA – Studien zur Agrarökologie, Band 34

Hamburg 2013, 204 Seiten
ISBN 978-3-8300-7456-4 (Print), ISBN 978-3-339-07456-0 (eBook)

Available Phosporhus, Available Pottasium, Beijing, Carbon, Fertilizer Recommendations, Geoökologie, N-Incubation Experiment, N-Mineralisation, Nitrogen, North China Plain, Sulphur

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To arise by reason of industrialization China is becoming wealthier while environmental problems increase. Due to increasing animal product consumption, large specialized livestock systems lead to a livestock density of 11 livestock units per hectare in the Shunyi District of Beijing. The high livestock density leads to application of very high farmyard manure amounts on the cropland and results in an over-fertilization of the soils of the peri-urban area of Beijing. The main goal of this thesis was to give fertilizer recommendations to optimize the nutrient status of soils in the Shunyi and Huairou Districts of Beijing. From 2009 to 2011 studies of the current status of soils for carbon ©, nitrogen (N), phosphorus (P), potassium (K) and sulphur (S) of 26 farmers’ field plots in the Shunyi and Huairou Districts with the five main cropping systems (winter wheat/summer maize, Chinese cabbage/spring maize, vegetables, orchards and poplars) were conducted. The soils are characterized as Eutric Cambisols with silty-loamy texture. Additionally, plots of a long-term field experiment in the Changping District were observed. Soil measurements revealed high contents of hot-water soluble carbon in soils which is an indicator for the emission potential of carbon to groundwater or the atmosphere. On the other hand, the soil organic matter (SOM) content is low. Even 14 years of organic fertilization could not increase the SOM content significantly (long-term experiment). Farmer’s surveys and nutrient balance calculations of the major cropping systems revealed that very high farmyard manure amounts are being applied to these fields and additionally mineral fertilizer. These high nutrient inputs as well as high atmospheric deposition resulted in very high mineralizable nitrogen contents in the soils. Additionally, available phosphorus, available potassium and sulphur show also high soil contents except at wheat/maize rotations and poplar plantations. This showed a need for fertilizer reduction. Therefore, new fertilizer recommendations in relation to cropping systems, soil nutrients and fertilizer type (pig manure, cattle manure, sheep manure, chicken manure, biogas plant effluent and compost) were calculated. For a better understanding of the different processes in the N cycle further experiments were carried out. In a laboratory incubation experiment under optimum conditions N mineralization was conducted. The laboratory N mineralization experiment revealed a potential N mineralization of 126-684 kg N ha-1 after one year. Additionally, an in situ N mineralization experiment was performed and revealed a low N mineralization of 28-56 kg N ha-1 (May-July) in the field. Moreover, measurements on the nitrogen loss via ammonia (NH3) volatilization in a maize field in summer were performed. Ammonia volatilization is an important pathway of nitrogen loss in these cropping systems and accounted for 1-16% of the applied N differing with substrate (biogas plant effluent, compost, fresh pig manure and urea) in a maize field. Biogas plant effluent (4.5%) as well as compost (3%) showed low NH3 volatilization therefore these substrates are recommended for fertilization. The soils were found to be calcareous with alkaline pH, but a pH drop was observed in the upper depth increment. However, liming should be considered in the future due to high fertilizer inputs and atmospheric deposition. It is shown that the fields of the Shunyi and Huairou District are over-saturated with nutrients and reduced fertilization is recommended. It is important that not only mineral fertilizers are applied, but also organic fertilizers to increase soil organic matter. Despite that, livestock density has to be reduced to 3-4 livestock units per hectare. Until then nutrients from farmyard manure (FYM) should be exported as compost to nutrient depleted soils in the North China Plain.

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