11.1 About Principle Investigator

Short Curriculum Vitae

A short impression

After finishing secondary education, I moved to Wageningen Agricultural University where I qualified cum laude with an MSc in environmental sciences in 1996. Later on I finished my PhD thesis at the same university. Since then, I have been working at several companies and research institutes.

During my professional career, I have focused on solid waste management (e.g. manure) and abatement of air-borne emissions, both in agricultural and industrial settings.

I am driven by the desire to find practical solutions for complicated problems, building on my R&D background as scientist and process engineer.

Selected peer-reviewed publications on manure treatment

1)      Vu, P.T., R.W. Melse, G. Zeeman, P.W.G. Groot Koerkamp (2016). Composition and biogas yield of a novel source segregation system for pig excreta. Biosystems Engineering Vol 145 pp 29-38.

2)      Melse, R.W.; M. Timmerman (2009). Sustainable intensive livestock production demands manure and exhaust air treatment technologies. Bioresour. Technol. Vol 100 No 22 pp 5506-5511.

3)      Melse, R.W.; Verdoes, N. (2005) Evaluation of four farm-scale systems for the treatment of liquid pig manure. Biosyst. Eng. Vol 92 No 1 pp 47-57.

For a complete list of my publications, please visit:

https://scholar.google.com/citations?user=3o8RPM8AAAAJ

11.2 Objectives of the study

The aim of this work package is to analyse and identify sustainable manure treatment techniques that are suitable for application in the Chinese dairy industry. These techniques must be able to further close the mineral cycles (N, P, K), comply with Chinese (legal) requirements and at the same time be economically feasible (i.e. not lead to extreme raise of milk price).

11.3 Main report of the research

As a first step, two fact-finding missions were conducted. Researchers from China Agricultural University and Wageningen UR Livestock Research visited eight dairy farms and biogas installations in Beijing Municipality, Hebei Province and Shanxi Province. One of the visited locations was the SDDDC demonstration farm (Zhongdi Farm).

Furthermore, knowledge exchange meetings took place with staff and students at the China Agricultural University and at the Chinese Academy of Agricultural Sciences. Also we hosted Assoc. Prof. QIAO Wei of CAU when he visited the Netherlands and paid a visit to several Wageningen UR environmental laboratories and several livestock research facilities.

Finally, a calculation tool for manure separation was made. This spreadsheet (both in English and Chinese language version) can be used to quickly estimate amounts and nutrient levels of liquid and solid manure fractions, produced by mechanical separation using a screw-press.

11.4 Conclusion

Generally speaking, cattle slurry and anaerobic digester effluent are valuable fertilizers that can be employed in feed and food production in an environmentally and economically justified way.

However, when large numbers of animals are concentrated in a relatively small area (as is the case in parts of China and The Netherlands), the available area of agricultural land may be insufficient for manure application. In that case, to avoid over-fertilization, the surplus manure should be transported to a region where it can be used responsibly as fertilizer on agricultural land. In our opinion, further research and extension should be aimed at increasing the manure nutrient efficiency. This means that losses to the environment (e.g. to groundwater tables, surface water, air) are minimized.

We propose to establish recommended and maximum nutrient application rates for nitrogen and phosphate from animal manure in China. Experiences in the Netherlands and other countries show that a combination of legislation and enforcement is essential to achieve the set goals and to prevent dumping of large manure volumes on small areas of agricultural land.

However, chemical analyses of the nutrient (N and P) contents of cattle slurry, anaerobic digester effluent, solid and liquid fractions and other manure products, are often lacking at the moment. Although these values are essential for the calculation of accurate crop specific fertilization rates, or the calculation of how much manure can be adequately utilized per mu (15 mu = 1 hectare). The development and dissemination of knowledge on the nutrient levels in organic fertilizers in relation to the nutritional needs of crops is highly desirable. This includes the interpretation by farm managers of the results of chemical analysis of organic fertilizers and soils.

Finally, we recommend to formulate farm specific ‘Manure Nutrient Management Plans’ for new large-scale livestock farms, in order to prevent the occurrence of manure surpluses at large-scale dairy farms without enough arable land. One of the main elements in such a plan is a calculation on how much manure and nutrients are produced per year, how this manure is treated or utilized on the farm or what happens with it when it is transported to other farms or companies. Plans for application of manure to crops must include a calculation of manure and nutrients application rates. This means that an inventory has to be made of regional opportunities for manure nutrient utilization in cattle feed and food crop production, prior to establishing a new livestock farm.

11.5 Appendix

11.5.1 Manure Management 2015 Progress Report

Impression of Datong Sifang Dairy Farm, Datong, Shanxi Province, China

11.5.1.1 Introduction

Sino-Dutch Dairy Development Centre (SDDDC)

In November 2013, China Agricultural University (CAU), Wageningen UR (WUR) and Friesland Campina launched the Sino-Dutch Dairy Development Centre (SDDDC) in Beijing. The objective of the Centre is to improve dairy production, safety and quality levels throughout the entire dairy chain in China. The SDDDC’s activities focus on sharing Dutch dairy expertise with Chinese experts and decision makers in dairy research and the dairy industry.

Public-Private-Partnership (PPP) Sino-Dutch Dairy Development Centre

The activities of the Expertise Centre entail Research, Innovation, Education, Training and Demonstrations. Within the PPP the focus lies on fundamental and applied research:

• Perform high-profile Research Projects on current Chinese dairy safety and quality issues and involve and engage relevant Ministries
• Support an Expertise Centre in China where safety and quality systems can be put into practice
• Cultivate talent, by facilitating student and faculty exchange and setting up training courses

Five Work Packages (PPP’s) within SDDDC

The following Wageningen UR projects were formulated for 2015:

·        WP1: Corn/hay production and feeding efficiency

·        WP2: Farm size development in China

·        WP3: Milk quality

·        WP4: Farm management

·        WP5: Manure Management

This progress report describes the findings and activities within WP5 "Manure Management" for the year 2015 (Project Leader: Dr. Roland W. MELSE). This project is linked to the CAU-project 2015-R2 "Sustainable Dairy Manure Management" (Project Leader: Dr. DONG Renjie).

11.5.1.2 Background

(1) Rapid growth and upscaling of the dairy sector in China

Considering income levels, population, urbanization and consumer preferences, it is estimated that the annual growth rate of dairy cattle number will be 5 – 7.5 % in China, so the total number of dairy cattle may reach 13.5 to 16 million in 2016 and 2020 respectively.

 In traditional dairy farming (with a cow yard outside the barn), the cow yard is a prominent agricultural nonpoint source of pollution. Most cow yards don’t have facilities to prevent liquid waste from leaching, sewage drainage or rain water and sewage separation measures, so that the nitrogen, phosphorus and other pollutants from urine and manure seep, leak or flow and thus pollute the environment.

In 2014, the Ministry of Agriculture continued to launch standardized large-scale dairy farm construction projects across China, and promoted demonstrations of standardized livestock farming. At the same time, some large dairy enterprises and large scale farming enterprises are accelerating construction of their dairy farms. These include more and more large-scale dairy farms which own thousands and even tens of thousands of dairy cattle. In recent years, due to the impact of rising feed costs, labor shortages and low efficiency, small household farmers are gradually tending to establish farming communities or household farms and most will choose to exit the dairy farming industry. Therefore, the development of large-scale farms will continue and is expected to account for 50 % of dairy farms in 2020. In Table 11-1 the characteristics of the major types of dairy farms are summarized; in Figure 11-1 the distribution of farm scales is shown for the regions in China.

In the past, most dairy farmers were backyard farmers with 3-10 cows. Fermenting and composting manure to use as fertilizer for crops was a virtuous circle and a quite environmentally-friendly approach. However, as the size of farms expands, it becomes more difficult to discharge and dispose of the waste and manure. More and more manure from bigger scale dairy farms has been discharged onto public land, and is polluting the environment. New regulations (see below) makes the newly built dairy farms feel pressure about dealing with environment control.

(2) Observations and recommendation from SAIN

Several years ago a China-UK Sustainable Agriculture Innovation Network (SAIN) was established to provide a framework for the development and implementation of collaboration on environmentally sustainable agriculture. Within this framwork several reports and papers were published. One of the papers was on "Improving Manure Nutrient Management in China", of which the main observations and recommendation are summarized below[1]:

·        3060 million tonnes (fresh weight) of livestock manure was generated in China in 2010. The N, P2O5 and K2O content of these manures is estimated to represent ca. 14 million, 10.2 million and 12.0 million tonnes respectively, which is worth ca. 201,300M RMB (based on 5.4, 5.5, 5.8 RMB per kg N, P2O5 and K2O, respectively),

·        Manure is commonly over-applied to horticultural crops, particularly greenhouse vegetables and fruit, which causes negative environmental impacts,

·        The barriers for effective management of manure, compost and digestate include lack of labour to transport and apply to the field, lack of knowledge of the nutrient content and availability and inadequate labelling of e.g. composted manure products;

·        The pathways for improved manure nutrient management include:

o   Retaining nutrients through the manure management continuum,

o   Using an integrated nutrient recommendation system,

o   Generating knowledge of the nutrient content and nutrient availability of manure, compost and digestate,

o   Ensuring CAFOs have manure nutrient management plans for utilisation in the local area (planning regulations),

o   Encouraging and incentivising improvements in other infrastructure, e.g. to facilitate mechanised transportation and spreading of manures.

(3) New regulations on prevention and control of pollution from CAFO's

New national regulations on large-scale livestock farm pollution control came into effect in 2014. The new regulations demand an environmental impact assessment plan to be written and also require the construction of facilities for pollution prevention and control. Furthermore, the new regulations state that the central government encourages and supports the elimination and utilization of animal wastes by integrating animal production and crop production. When manure or manure products are used for fertilization of crops, the application shall not exceed the carrying capacity of the land in order to prevent environmental pollution. However, in these regulations no numbers are given on maximum amounts of nutrients (N or P) or manure that may be applied to the land. In order to reduce environmental pollution, we feel that strict regulations are necessary that outline how much manure can be adequately utilized per mu, and therefore is allowed to be applied.

11.5.1.3 Activities carried out in 2015

 (1) Fact-finding missions

In June and September 2015, two fact-finding missions in the field of WP5-Manure Management were conducted. Researchers from China Agricultural University and Wageningen UR Livestock Research visited eight dairy farms and biogas installations in Beijing Municipality, Hebei Province and Shanxi Province. One of the visited locations was the SDDDC demonstration farm (Zhongdi Farm). The locations were selected in consultation with the staff of SDDDC and China Agricultural University. In Table 11-2 the visited farm locations are shortly described.

The farms that were visited varied in livestock numbers as well as in the applied manure treatment technologies, ranging from no treatment at all to slurry flushing systems, biogas technology, mechanical slurry separation and tunnel composting of the solid fraction. In the next chapters the main findings from these visits are presented and discussed.

(2) Knowledge exchange meetings

Knowledge exchange meetings took place with staff and students at the China Agricultural University (September 23rd, 2015, Assoc. Prof. QIAO Wei) and with staff and students at the Chinese Academy of Agricultural Sciences (September 18th, 2015, Prof. DONG Hongmin). During these meetings, both the Dutch and the Chinese situation regarding manure nutrient management, gaseous emissions and environmental policy were discussed.

A return visit of Assoc. Prof. QIAO Wei of CAU to the Netherlands on September 30th/October 1st, 2015 made it possible to visit several Wageningen UR environmental laboratories and several livestock research facilities (research accomodation CARUS in Wageningen and dairy cattle demonstration farm ‘De Marke’ in Hengelo, Gld).

(3) Calculation tool for manure separation

One of the basic technologies for manure (slurry) treatment is the separation of slurry (or digestate) into a solid fraction and a liquid fraction. Often a screw-press is used (see next chapter) the produced solid and liquid fractions can be used for further processing or can be used directly for fertilization. Although separation can be regarded as a simple technique, it is often not entirely clear how the nutrients and dry matter are distributed between the two fractions.

In order to provide more insight into nutrient concentrations and total amounts of nutrients, dry matter and mass flows, a calculation tool was developed. The spreadsheet can be used to quickly estimate amounts and nutrient levels of liquid and solid manure fractions, produced by mechanical separation using a screw-press. In this way, the spreadsheet may help farm managers that are thinking about buying slurry separation equipment by predicting what products they can expect. Furthermore, farms that already have separation equipment can get insight in how increasing or decreasing the separation efficiency will affect the amounts and nutrient contents of the products.

The inputs of the spreadsheet (that can be changed by the end-user) are:

·        the characteristics of the slurry (contents in kg/ton);

·        the performance of the screw-press, as defined by mass separation efficiency (%) and dry matter content (kg/ton) of the solid fraction produced;

·        the manure production per year (number of cows and slurry production per cow per year).

Using this data, the spreadsheet calculates the nutrient contents and amount of the solid and liquid fractions, including the distribution (in%) of nutrients between the fractions. Furthermore, a mass balance for a one-year period is shown.

The spreadsheet calculation tool will be made available on the SDDDC website (http://sdddc.org), both in an English and a Chinese language version.

11.5.1.4 Results of fact-finding missions

(1) Manure collection, treatment and storage

The most advanced manure treatment systems encountered where those with automated scrapers on concrete floors and flushing of the scraped manure through channels with the liquid fraction from manure separation (location 2 and 8) or with water (location 3 and 5), biogas production (location 6 and 7) and slurry separation with screw press filters (location 3, 5, 6, 7 and 8). At one location (location 2) we encountered the combination of an inclined screen separator with a screw press filter. The solid fraction from manure separation, fresh (most farms) or composted (location 8), is either used for bedding or sold to vegetable growers. At one location (location 5) there was no demand for solid or liquid fraction, due to absence of sufficient vegetable growers nearby. However, separation was applied. The liquid fraction from slurry separation is mostly stored in open lagoons for subsequent use as a liquid fertilizer. At many farms these types of lagoons are not covered. At Zhongdi Farm most lagoons are covered with a floating cover, which will substantially reduce emissions of ammonia.

In figure 11-2 to figure 11-7 some pictures are given that show the present equipment and facilities on some of the farms.

Figure 11-2 A typical large-scale dairy farm; cubicles with solid manure bedding and scraped concrete floors, Datong Sifang Dairy, Datong, Shanxi Province.

Figure 11-3 Horizontal biogas reactor, partly below ground, at Modern Farming Saibei Farm, Hebei Province.

Figure 11-4 Combination of an inclined screen separator and a screw press filter for slurry separation, Zhongdi Farm, Beijing Municipality.

Figure 11-5 Solid manure from slurry separation is used as bedding material in the cubicles, Modern Farming Saibei Farm, Hebei province.

Figure 11-6 Covered lagoon storage of liquid fraction from slurry separation, Zhongdi Farm, Beijing Municipality. Note the gas production under the cover.

Figure 11-7 Tunnel composting of solid manure fraction, Datong Sifang Farm, Datong, Shanxi Province.
Composted manure is sold for 40 – 50 RMB (≈ 6 – 7 Euro) per ton.

(2) Manure application

Most cattle farms do not own agricultural land, so manure has to be sold and/or transported to other arable farms. Solid manure is normally transported in open trucks and mostly used as fertilizer for vegetable crops. Liquid manure is applied to agricultural land either by spreader trucks (see Figure 11-8 for an example) or by irrigation.

Figure 11-8 Filling the manure spreader with the liquid fraction from digestate separation, Modern Farming Saibei Farm, Hebei Province.

(3) Nutrient flows and distribution between solid and liquid fraction

When cattle slurry (with a dry matter content of approx. 10 %) is separated with a screw press filter, the mass of the input slurry (100 %) is divided into 15 – 25 % of solid fraction by mass and 75 – 85 % of liquid fraction by mass. The solid fraction has a dry matter content of 20 – 40 % and the liquid fraction has a dry matter content of 5 – 7 %.

Extensive testing of different screw press filters with cattle slurry in the Netherlands revealed that approximately 15 - 20 % of the nitrogen (N) and 20 - 35 % of the phosphate (P2O5) is transferred to the solid fraction, depending on the initial slurry dry matter content and the performance of the screw press separator. Consequently, 80 - 85 % of the nitrogen and 65 – 80 % of the phosphate remain in the liquid fraction which also constitutes the largest volume share.

For more information, please consult the Spreadsheet Calculation Tool for slurry separation with a screw press filter, described in 11.5.1.3, paragraph (3).

(4) Nutrient losses

Based on literature, the following major sources of nutrient losses from manure treatment, storage and application can be distinguished:

·        Uncovered lagoons (emissions of ammonia NH3 and methane CH4),

·        Solid manure storage and composting (nitrogen loss up to 60 %),

·        Superficial application of manure without immediate mixing or covering with soil (ammonia emission, phosphate run-off),

·        Manure application outside the growing season of crops (ammonia emission, nitrate leaching, phosphate run-off and leaching),

·        Manure application with nutrient loads far in excess of the crop uptake (exceeding Good Agricultural Practice application standards for nitrogen and phosphate). Nutrients that are not used by crops will be lost.

For two large cattle farms that were visited estimations were made of the yearly manure nutrient production and the manure nutrient supply (N and P2O5) per hectare of agricultural land. Both farms use the liquid fraction from a screw press separator for irrigation of crops on a significant and known area of agricultural land.

The calculations are based on the assumptions that the manure production per cow in China and in the Netherlands is the same (comparable milk production levels), that the manure from large scale modern intensive cattle farms in China has the same nutrient levels as in the Netherlands (comparable diet compositions) and that screw press filters, made in China, have a comparable separation performance for nutrients as screw press filters made in the Netherlands. The results of the calculations are presented in Table 11-3. Note that possible nitrogen losses from long-term lagoon storage of the liquid fraction prior to land application and the possible effect of sedimentation of phosphate are not taken into account.

As a reference, the legal maximum application rates for nitrogen and phosphate on agricultural land in 2015 in the Netherlands are 385 kg N/hectare/year and 100 kg P2O5/hectare/year for highly productive grassland (1 hectare = 15 mu). The application rates in the Netherlands are based on nutrient removal by crop uptake, i.e. that the aim is to achieve a balance between nutrient input and output of the land.

Although the nutrient application rates on the two farms in Table 11-3 must be regarded as rough estimates, it is clear that the nitrogen and phosphate application rates, applied on the two Chinese farms are 7 to 10 times higher than the maximum application rates in the Netherlands (only valid for highly productive grassland without grazing). Phosphate content (P2O5) is calculated as 2.29 times the analysed phosphorus (P) content in fertilizers/manure. If more than one crop per year is grown (which is the case for most farms that we visited), higher application rates can be justified. But even then, application rates are still much higher than the maximum rates that are used in the Netherlands.

In the Netherlands, the maximum application rates for corn are 185 kg/ha/year and 75 kg/ha/year, for N and P2O5, respectively. For winter wheat, the maximum rates for N and P2O5 are 245 kg/ha/year and 75 kg/ha/year, respectively.

Nitrogen losses from and phosphate sedimentation in the lagoons requires further study.

(5) Anaerobic Digestion

Controlled anaerobic digestion, i.e. the production of biogas from liquid manure, is an interesting option for the production of renewable energy at large dairy farms. Biogas is mainly composed of 55-60 % combustible methane (CH4) and 30-35 % carbon dioxide (CO2). By application of anaerobic digestion technology, the uncontrolled emission of methane from slurry storage can be reduced. The emission of methane is unwanted, because it is a potent greenhouse gas (25 times more powerful than CO2). After removal of the toxic and corrosive component hydrogen sulphide (H2S) that may be present in biogas at an acutely lethal concentration of 3.000 ppm (0.3 %) and more, biogas can either be used as fuel in a Combined Heat and Power (CHP) unit for the production of electricity (e.g. at location 7), or used as such for household purposes like cooking and heating (e.g. at location 6).

Lagoons for the storage of untreated cattle slurry or liquid fraction from slurry separation can be transformed into a biogas reactor by covering the lagoon with a gas-tight foil and collection of the biogas that is produced under the cover. Even if the produced biogas is not used, flaring of the biogas in a biogas burner is preferred over release of biogas to the atmosphere in order to prevent the significant greenhouse gas emission of methane.

The liquid fraction from separation of fresh manure with a screw press filter has a relatively high biogas potential, only slightly less than the biogas potential of fresh slurry. The required residence time in a biogas reactor is shorter (e.g. 3 weeks) than for unseparated slurry (e.g. 7 weeks), since the larger organic particles that require a longer residence time are already removed by the separator. Therefore the volume of the biogas reactor can be proportionally smaller. Furthermore, mixing and pumping of the liquid fraction requires less energy because of the lower viscosity of the liquid. When the waste heat of a CHP-unit is used for heating (e.g. the biogas reactor, offices, milking parlour), the use of coal for heating can be reduced.

The economic viability of the anaerobic digestion of only cattle slurry should be established case by case, since anaerobic digestion of only cattle slurry in the Netherlands is not economically feasible, despite government subsidies for renewable energy. The investment costs and manure disposal costs in the Netherlands are the main obstacles. In China, the cost calculations could lead to a different outcome.

Digestate, the effluent from anaerobic digestion of cattle manure, has the same nutrient levels as undigested, fresh manure, although the rapid availability of some nutrients (primarily nitrogen) for plant growth is somewhat increased by the decomposition of organic matter and related increase in pH-value (from pH 7.5 to pH 8.0 - 8.5). Organic carbon (C) is transformed into methane CH4 and carbon dioxide CO2, the main constituents of biogas.

11.5.1.5 Conclusions and recommendations

Generally speaking, cattle slurry and anaerobic digester effluent are valuable fertilizers that can be employed in feed and food production in an environmentally and economically justified way.

However, when large numbers of animals are concentrated in a relatively small area (as is the case in parts of China and The Netherlands), the available area of agricultural land may be insufficient for manure application. In that case, to avoid over-fertilization, the surplus manure should be transported to a region where it can be used responsibly as fertilizer on agricultural land.

In our opinion, further research and extension should be aimed at increasing the manure nutrient efficiency. This means that losses to the environment (e.g. to groundwater tables, surface water, air) are minimized. The nitrogen losses from lagoons and phosphate sedimentation in the lagoons requires further study. Besides reducing losses to the environment, increasing manure nutrient efficiency also means that expenses for chemical fertilizer purchase can be reduced. Unavoidable nutrient losses following manure application (approx. 40-80 % of total N, depending on manure type and application technology) can be compensated with chemical nitrogen fertilizer.

We suggest to establish recommended and maximum nutrient application rates for nitrogen and phosphate from animal manure in China. These application rates may be differentiated with regard to crop and soil types and different climate zones in China. In the meantime, provisional application standards could be established for nitrogen and phosphate fertilization per mu (from animal manure and from chemical fertilizers). In this way all stakeholders (farmers, extension, officials etc.) can gain experience with using application standards. Finally, experiences in the Netherlands and other countries show that a combination of legislation and enforcement is essential to achieve the set goals and to prevent dumping of large manure volumes on small areas of agricultural land.

Chemical analyses of the nutrient (N and P) contents of cattle slurry, anaerobic digester effluent, solid and liquid fractions and other manure products, are often lacking at the moment. However, these values are essential for the calculation of accurate crop specific fertilization rates, or the calculation of how much manure can be adequately utilized per mu (15 mu = 1 hectare).

The development and dissemination of knowledge on the nutrient levels in organic fertilizers in relation to the nutritional needs of crops is highly desirable. This includes the interpretation by farm managers of the results of chemical analysis of organic fertilizers and soils.

Figure 11-8 Taking samples of composted manure for laboratory analyses of the nutrient content, indispensable for the calculation of 'how much manure can be adequately utilized per mu' (15 mu = 1 hectare). Datong Sifang Dairy Farm, Datong, Shanxi.

Finally, we recommend to formulate farm specific ‘Manure Nutrient Management Plans’ for new large-scale livestock farms, in order to prevent the occurrence of manure surpluses at large-scale dairy farms without enough arable land. One of the main elements in such a plan is a calculation on how much manure and nutrients are produced per year, how this manure is treated or utilized on the farm or what happens with it when it is transported to other farms or companies. Plans for application of manure to crops must include a calculation of manure and nutrients application rates. This means that an inventory has to be made of regional opportunities for manure nutrient utilization in cattle feed and food crop production, prior to establishing a new livestock farm.

11.5.2 Spreadsheet for manure separation
Calculation tool for manure separation, download link: http://www.sdddc.org/en/download/detail-155.aspx