Flow of Manure Nutrient, Floor Space Allowance and Nitrogen Fertilization Practice (Rice Farming) in Integrated Crop-Animal Farming System

Abstract

An integrated crop-animal farming (ICAF) refers to a management system that establishes a sustainable agricultural environment and ecosystem by reusing the by-products between the livestock farms and the crop farms in the agricultural system. Understanding the balance of nutrients from the generation of livestock manure to the land-application of plant-soil system is considered to be one of the important factors in establishing the ICAF system. However, it is not easy to understand the relationship of each factor and find a balance point because the complex processes are linked in the ICAF system. Therefore, this dissertation analyzed the nutrient flow and dynamics from livestock manure production to land-application in South Korea. The nutrient flow of pig manure in the ICAF system was analyzed by applying appropriate FSA considering pig productivity. In addition, a suitable method of using chemical fertilizer and treated swine slurry was proposed. As a result, the following conclusions were obtained. First, the ICAF system in South Korea is still inadequate and has been suffering from the disposal of livestock manure and agricultural waste in many areas. Therefore, it was necessary to closely examine the ICAF status of the relatively active areas (Nonsan and Namwon) and to find out the ICAF system considering the characteristics of the poor ICAF areas (Yeongcheon and Jinju). In Jinju, the urbanization rate was relatively high. Therefore, the ICAF system was considered to be suitable for the two-track model that co-promotes the compost/liquid fertilizer facility and the energy facility. In the case of Yeongcheon, it would be appropriate to install three to four decentralized public recycling facilities at midsize (around 30 tons) in myeon where a cluster of livestock farms was located. However, according to scenario predictions, the recycling rate of livestock manure in the area had increased but the over-supply of nutrients had not decreased. Comparing the nutrient requirement of the crop with the amount of nutrient input to the cropland, it can be seen that 113 kg ha-1 of N and 146 kg ha-1 of P2O5 were over-supplied annually. In Jinju, 12 kg ha-1 yr-1 of P2O5 was expected to have an oversupply in comparison with the amount of nutrients required for crops. Even if the ICAF system is built in consideration of local characteristics, the use of large amounts of livestock manure and indiscriminate application of chemical fertilizers exceeding the capacity of agricultural land remains a problem. Second, the appropriate level of floor space allowance (FSA) is probably the most important factor in managing this large-scale pig farms. In particular, the pig farming industry in South Korea prefer to pursue profit by maximizing the production of pigs in a limited space as much as possible. As a result, farmers (producers) are guaranteed a certain level of productivity, but livestock, farm managers, and people around the farm cannot avoid the negative impact. In this dissertation, the average survival rate (SR) of growing pigs tended to increase with increasing FSA. Generally, fattening pigs in South Korea were being raised in a small space. Therefore, it was found that if the FSA of 0.8 ~ 1.0 m2 head-1 is increased to 1.1 ~ 1.27 m2 head-1, it contributed to raise the average SR. The days at a slaughter weight of 110 kg (d-SW) of fattening pigs also showed a tendency to decrease with increasing FSA. It is considered that the fattening pigs raised in moderately wide space (1.27 ~ 1.54 m2 head-1) were helpful for the increase of the growth rate due to the stress reduction. A slight increase in the FSA can have a positive impact on productivity, while also solving environmental problems. As FSA increased, the amount of nutrients (N, P2O5 and K2O) from livestock manure was reduced. In the case of N, 20%, 27%, 37% and 48% of N were reduced in 1.0 m2 head-1, 1.1 m2 head-1, 1.27 m2 head-1 and 1.54 m2 head-1, respectively, compared to the N value of 0.8 m2 head-1. Other nutrients (P2O5 and K2O) were also reduced at a similar rate. According to the nutrient flow calculation method of the four regions (Namwon, Nonsan, Yeongcheon and Jinju), increasing the FSA from 0.8 to 1.54 m2 head-1 resulted in a reduction of surplus N up to 60%. In the case of P2O5, 5% ~ 16% was reduced as the FSA increased, and the deviation by region excluding Jinju was not large. Jinju showed the highest surplus P2O5 reduction (61%) compared to other regions probably due to the large cropland area per livestock unit (LU). Third, the use of proper N fertilizer in rice farming is an essential factor in the success of farming. The N fertilization practices using organic fertilizers (livestock manure) with chemical fertilizers are being used as part of sustainable agriculture. When using anaerobically-aerobically treated swine slurry (TSS) and chemical fertilizer (AS) in combination, it is preferable to use the chemical fertilizer less than 3:1 ratio since the recovery of inorganic N was constant regardless of the mixing ratio of AS. In the oxidized topsoil of paddy soils, NH4+ was converted to NO3- by the effect of nitrification process. As a result, it was predicted that the soil δ15N level increased as the 14NH4+ decreased. Total 15N recovery (crop + soil) was 42%, 43% and 54% in HTSS + LAS (3:1 ratio of TSS and AS), LTSS + HAS (1:2 ratio of TSS and AS) and AS (chemical fertilizer only), respectively. The N fertilization practice with low AS and high TSS rates was recommended for sustainability and cost savings. However, N losses, especially through the coupled nitrification-denitrification process, can diminish the benefits that HTSS+LAS offers. In the introduction of this dissertation, the current status and problems of the overall livestock production in South Korea were described. In chapter 2, two regions (Yeongcheon and Jinju) operated as individual recycling facilities and two regions operated by public recycling facilities (Namwon and Nonsan) were selected to investigate the dynamics of livestock manure nutrients. The potential nutrient supply and nutrient requirements of crops were analyzed. Chapter 3, in conjunction with the content of Chapter 2, examined the appropriate FSA that satisfies both productive and environmental aspects. Chapter 4 discussed the land-application of livestock manure for the next phase of the livestock manure disposal and treatment process (discussed in chapter 2). The N behavior of paddy soils using TSS + AS mixed fertilization practices was investigated. Conventional land-application studies on livestock manure were based primarily on fertilizer value and crop productivity of compost / liquid fertilizer. This thesis is different in that it can analyze the N behavior of the soil-crop system more accurately by using 15N and proposed appropriate TSS and AS fertilization practices compared with existing methods. In particular, anaerobically-aerobically treated pig slurry was used as a fertilizer resource in paddy soils. This is a study on the follow-up process of renewable energy of livestock manure and can be regarded as an academic contribution of this thesis. It is hoped that guidelines on the land-application of livestock manure in various agricultural sectors such as horticulture, upland, fruit trees, grass land as well as paddy soil will be created on the direct / indirect extension of this thesis.