畜禽粪便资源现状及替代化肥潜力研究:以安徽省固镇县为例

基于养殖业和种植业发展现状,综合考虑农作物种植面积、种植结构以及畜禽粪便处理技术等因素,估算固镇县分乡镇的固液粪便养分资源现状及其替代化肥的潜力。结果表明:(1)固镇县畜禽粪便中氮和磷养分量分别为11 456.93和2 954.09 t;在不施用化肥和不进行秸秆还田的情景下,各乡镇畜禽粪便的氮、磷供给量均未超过作物氮、磷养分需求量。(2)情景模拟表明,情景C(固体粪便收集后尽快经堆肥加工为有机肥,液体粪便收集生成沼气后其废物本地还田利用)为最佳模式,氮和磷的有效供给量分别为8 948.78和2 642.37 t,分别占作物氮、磷需求量的34%和54%,表明固镇县有足够的农用地消纳畜禽粪便,亟需改进畜禽粪便处理工艺,提高粪肥替代化肥潜力。(3)在情景C下,畜禽粪便中氮、磷养分替代化肥潜力为4 715.04和1 247.07 t,仲兴乡、任桥镇、刘集镇和杨庙乡替代化肥潜力最大。研究结果可为固镇畜禽养殖业发展规模的确定和畜禽粪便资源化利用提供决策支持。

甘肃省天水市畜禽粪肥资源现状及替代化肥潜力研究

综合考虑农作物种植结构、种植面积及畜禽粪污处理方式等因素,估算了天水市各县区粪污养分资源现状及其替代化肥的潜力。结果表明,天水市畜禽粪污中氮、磷养分分别为22565.01t和3384.75t,且各县区畜禽粪污氮和磷供给量均未超过作物需求量;当前天水市大部分养殖场固体粪污储藏堆放还田,液体粪污直接还田,在这种粪污处理方式下,氮、磷的有效供给量分别占作物氮、磷需求量的10.49%和6.72%,表明天水市有足够的耕地消纳畜禽粪污;研究还发现:在固体粪污加工为商品有机肥,液体粪污沼气处理的方式下,粪肥养分损失率最低;各县区氮养分的替代率高于磷养分替代率;我市粪肥替代化肥潜力较大,应提高粪污资源化利用水平。研究结果可为天水市畜禽粪污资源化利用和确定养殖业发展规模提供理论依据。

The land-sourced pollution in the Jiaozhou Bay

In recent years, natural environment of the Jiaozhou Bay has been changed largely by fast developing industry and agriculture of the cities around, from which wastewaters were generated. The size of the bay has been continuously shrunk with reduced river flows, resulting in serious contamination to the marine lives in the bay. After analyzing the basic historical data, the authors put forward a suggestion of how to protect the bay ecology for sustaining the resources in the Jiaozhou Bay.

Spatial Variation of P and N in Water and Sediments of Dianchi Lake, China

Dianchi Lake is one of the most eutrophic lakes in China. In order to understand this eutrophication and to help control the pollution, this research investigated the spatial distribution of Kjeldahl nitrogen (K-N) and total phosphorus(TP) through analysis of bottom water and sediment (3 depths) samples collected at 118 sites around Dianchi Lake. The concentrations of K-N and TP for the lake bottom water in the Caohai part of the lake were much higher than those in the Waihai part, generally decreasing from north to south. In the sediments, the K-N concentration was higher in the Caohai part and the middle of the Waihai part. On the other hand, TP in the sediments was greater in the southern and western parts. Both K-N and TP had similar spatial distributions for the sediment samples of three different depths.Vertically, the K-N and TP concentration in the sediments decreased with an increase in depth. This was evidence that eutrophication and pollution of Dianchi Lake was becoming gradually more severe. Exterior factors including uncontrolled input of domestic and industrial effluents as well as non-point pollution around the lake were the main reasons for serious eutrophication; therefore, controlling these was the first step in reducing eutrophication of Dianchi Lake.

Degradation of Soil Nutrients in Southeast China

A total of 2 190 soil nutrient data in the Second National Soil Survey of China were collected to assess thedegradation of soil nutrients in the hilly region of Southeast China. The definition of soil nutrient degradationis suggested firstly then the evaluation criteria are set up and the current status of degradation of red soil and latosol is assessed. The percentages of areas in four grades of soil nutrient degradation, i.e., slightlydeficient, medium deficient, severely deficient and extremely deficient, were 21.3%, 43.3%, 16.2% and 3.0%for soil total N; 0.7%, 6.4%, 16.7% and 76.2% for soil available P; and 25.4%, 26.3%, 8.6% and 5.0% forsoil available K, respectively. The severity of soil nutrient degradation was in the order of P > N > K. Themajor factors leading to the degradation of soil nutrients in quantity include soil erosion, leaching and theconsumption by crops. And the principal faCtor affecting the degradation of soil nutrieots in availability isthe fixation of N, P and K, especially the fixation of phosphorus. The average amouat of P fixed by soils is408 mg kg-1, and upland soils can fix more P than paddy soils.

N limitation increases along a temperate forest succession:evidences from leaf stoichiometry and nutrient resorption

Forest productivity and carbon(C) sequestration largely depend on soil N and P availability.To date,however,the temporal variation of nutrient limitation along forest succession is still under debate.Leaf stoichiometry and nutrient resorption are important indicators for predicting nutrient limitation of plant growth.Here,we measured nitrogen(N)and phosphorus(P)concentrations in green leaves and leaf liter for all woody species at four stages of temperate forest succession,and analyzed how abiotic and biotic factors affect leaf stoichiometry and nutrient resorption along forest succession.At the individual scale,leaf N and P concentrations had a significant increase at the end of the succession,while no change in leaf N:P ratio was detected.Nitrogen resorption efficiency(NRE)increased significantly with succession,but P resorption efficiency(PRE)first increased and then decreased.Significant increases in NRE:PRE ratios only occurred at the end of the succession.Moreover,plant N cycling was less responsive to soil nutrient than P cycling.At the community scale,we found that leaf N and P concentrations first decreased and then increased along forest succession,which were mainly affected by Shannon-Wiener index and species richness.Leaf N:P ratio significantly varied with succession and was mainly determined by community-weighted mean diameter at breast height(DBH).NRE increased and was significantly influenced by species richness and DBH,while PRE was relatively stable along forest succession.Thus,the NRE:PRE ratios significantly increased,indicating that N limitation is exacerbated with the temperate forest succession.These results might reflect the intense interspecific competition for limiting resource in a higher biodiversity community.In conclusion,our findings highlight the importance of biotic factors in driving forest ecosystem nutrient cycling and provide valuable information for sustainable fertilizer management practices in China's temperate and boreal forests.

Combined Applications of Nitrogen and Phosphorus Fertilizers with Manure Increase Maize Yield and Nutrient Uptake via Stimulating Root Growth in a Long-Term Experiment

Imbalanced application of nitrogen(N) and phosphorus(P) fertilizers can result in reduced crop yield,low nutrient use efficiency,and high loss of nutrients and soil nitrate nitrogen(NO_3^--N) accumulation decreases when N is applied with P and/or manure;however,the effect of applications of N with P and/or manure on root growth and distribution in the soil profile is not fully understood.The aim of this study was to investigate the combined effects of different N and P fertilizer application rates with or without manure on maize(Zea mays L.) yield,N uptake,root growth,apparent N surplus,Olsen-P concentration,and mineral N(N_(min)) accumulation in a fluvo-aquic calcareous soil from a long-term(28-year) experiment.The experiment comprised twelve combinations of chemical N and P fertilizers,either with or without chicken manure,as treatments in four replicates.The yield of maize grain was 82%higher,the N uptake 100%higher,and the N_(min) accumulation 39%lower in the treatments with combined N and P in comparison to N fertilizer only.The maize root length density in the 30-60 cm layer was three times greater in the treatments with N and P fertilizers than with N fertilizer only.Manure addition increased maize yield by 50%and N uptake by 43%,and reduced N_(min)(mostly NO_3^--N) accumulation in the soil by 46%.The long-term application of manure and P fertilizer resulted in significant increases in soil Olsen-P concentration when no N fertilizer was applied.Manure application reduced the apparent N surplus for all treatments.These results suggest that combined N and P fertilizer applications could enhance maize grain yield and nutrient uptake via stimulating root growth,leading to reduced accumulation of potentially leachable NO_3^--N in soil,and manure application was a practical way to improve degraded soils in China and the rest of the world.

Soil Respiration, Microbial Biomass and Nutrient Availability in Soil After Addition of Residues with Adjusted N and P Concentrations

Microbial activity and nutrient release are known to be influenced by organic matter properties,but it is difficult to separate the effect of C/N ratio from that of C/P ratio because in most plant residues both ratios are either high or low.An incubation experiment was conducted to investigate the effects of reducing the C/N and C/P ratios of slowly decomposable plant residues(young eucalyptus leaves,mature wheat straw,and sawdust) to those of rapidly decomposable residues(young kikuyu shoots) on soil respiration,microbial biomass,and N and P availability.The C/N and C/P ratios of the former were adjusted to 15 and 89,respectively,by adding N as(NH_4)_2SO_4,P as KH_2PO_4 or both and residues were added at 10 g C kg-1 to a silt loam.Soil respiration was measured over21 d;microbial biomass C(MBC) and available N and P were measured on days 0,7,and 21.Compared to the unamended soil,addition of kikuyu increased cumulative respiration 20-fold,MBC concentration 4 to 8-fold,and available P concentration up to4-fold,whereas the increase in available N concentration was small and transient.Cumulative respiration and MBC concentration were low in the sawdust-amended soil and were not influenced by reducing the C/N and C/P ratios.Cumulative respiration with original wheat and eucalyptus was 30%-40%of that with kikuyu.Reducing the C/N ratio alone or both C/N and C/P ratios increased cumulative respiration and MBC concentration 2-fold compared to the original wheat and eucalyptus,whereas reducing the C/P ratio had little effect.Throughout the experiment,the available N concentration after addition of residues with reduced C/N ratio increased in the following order of eucalyptus < wheat < sawdust.By independently lowering the C/N and C/P ratios,microbial activity was more limited by C and N than P.However,lowering the C/N ratio of very slowly decomposable sawdust had no effect on soil respiration and MBC concentration,suggesting that other properties such as concentration of poorly decomposable C compounds limited decomposition.

Environmental constraints on the inter-genus variation in the scaling relationship between leaf nitrogen and phosphorus concentrations

Aims The scaling relationship between nitrogen(N)and phosphorus(P)concentrations([N]and[P],respectively)in leaves manifests plants’relative investment between the two nutrients.However,the variation in this relationship among taxa as well as its causes was seldom described.Methods The analysis was based on a dataset including 2483 leaf samples from 46 genera of angiosperm woody plants from 1733 sites across China.We calculated the leaf N–P scaling exponent(βL)with an allometric equation([N]=α[P]β),for each genus,respectively.We then performed phylogenetic path analyses to test how the climate and soil niche conditions of these genera contributed to the inter-genus variation inβL.Important Findings The genera living with lower soil P availability presented a more favoured P uptake relative to N,as shown by the higherβL,suggesting a resistant trend to P limitation.Additionally,genus-wiseβL was positively correlated with soil N–P scaling exponents(β_(S)),implying that the variation in leaf nutrients is constrained by the variability in their sources from soil.Finally,climatic factors including temperature and moisture did not affectβL directly,but could have an indirect influence by mediating soil nutrients.Phylogeny did not affect the inter-genus variation inβL along environmental gradients.These results reveal that the trade-off between N and P uptake is remarkably shaped by genus niches,especially soil nutrient conditions,suggesting that theβL could be considered as a functional trait reflecting characteristics of nutrient utilization of plant taxa in response to niche differentiation.