Field experiments were conducted on three typical farmland soils (loess soil, fluvo-aquic soil, and cinnamon fluvo-aquic soil) in Northern China to study the grain yield, phosphorus agronomic efficiency (PAE), and phosphorus use efficiency (PUE) of wheat under effects of long-term fertilizations. Seven treatments were installed, i.e., non-fertilization (CK), nitrogen fertilization (N), nitrogen-potassium fertilization (NK), nitrogen-phosphorus fertilization (NP), nitrogen-phosphorus-potassium fertilization (NPK), NPK plus straw returning (NPKS), and NPK plus manure application (NPKM). The averaged wheat grain yields under long-term P fertilizations (treatments NP, NPK, NPKS, and NPKM) ranged from 2914 kg x hm(-2) to 6219 kg x hm(-2), being 200%-400% higher than those under no P fertilizations (treatments CK, N, and NK), and no significant differences were observed between the P fertilizations. In the early years of the experiment, the PAE in treatment NPK on the loess soil, fluvo-aquic soil, and cinnamon fluvo-aquic soil was 17.0 kg x kg(-1), 20.3 kg x kg(-1), and 13.3 kg x kg(-1), and the PUE was 15.3%, 31.2%, and 23.8%, respectively. After 15-year fertilization, the PAE and PUE in treatment NPK increased annually by 3.9 kg x kg(-1) and 1.3% on loess soil, 2.5 kg x kg(-1) and 0.9% on fluvo-aquic soil, and 2.8 kg x kg(-1) and 1.0% on cinnamon fluvo-aquic soil, respectively. There were no significant differences in the PAE and PUE among the P treatments for the same soils. In Northern China, long-term P fertilization could increase the wheat grain yield and PUE significantly, and the mean annual increase of PAE and PUE in treatment NPKM was higher on loess soil than on fluvo-aquic soil and cinnamon fluvo-aquic soil.
Abstract Stand level biomass carbon model is an important tool for forest resource inventory and monitoring. Developing biomass carbon models for major forest types in China not only provide a scientific basis for estimating forest carbon storage changes at national level, but also provide an important reference for estimating forest carbon storage and carbon sequestration potential at regional and global levels. In this paper, based on the measured data of 52,700 permanent plots from the 9th national forest inventory (NFI) of China, the biomass and carbon storage per hectare were firstly calculated according to the tree biomass models and carbon factors of 35 tree species groups. Then, stand level volume-derived biomass and carbon storage models were developed for 20 forest types by using the approach of simultaneous equations with error-in-variables. Secondly, based on the developed biomass and carbon models of 20 forest types, using the data of 1st to 9th NFIs of China and the area and volume data of different forest types in 1949 and 1950-1962, the forest carbon storages in different periods in the past 70 years and the carbon storages of planted forest in the past 40 years were estimated. Results showed that the determination coefficients (R2) of the developed biomass and carbon models of 20 forest types were more than 0.87, the total relative errors (TREs) were close to 0, and the mean prediction errors (MPEs) were less than 3% (less than 1% for 8 forest types). From the results of independent cross-validation, the TREs were within ±3% except one model, and the average systematic errors (ASEs) were all within ±5%. China's forest carbon storage was 5.89Pg in 1949, and decreased to the lowest level of 4.90Pg in the late 1970s. With the implementation of large-scale afforestation and key forestry programs such as natural forest protection, China's forest carbon storage gradually increased to 8.69Pg in the 9th NFI. Over the past 40 years, China's forest carbon storage has increased by 3.79Pg, of which 2.25Pg was from natural forest and 1.54Pg from planted forest. The applicability of three sets of published biomass models were tested with the data from this study, and it was found that there were large biases for all models, but the estimated results would be improved with the increase of modeling sample size. The biomass and carbon storage models of 20 forest types in China developed in this study would provide a quantitative basis for accurately estimating status and changes of forest carbon storage at national and regional levels. In the past 70 years, China's forest carbon storage has shown a U-shaped development trend. Both afforestation and natural forest protection have made great contributions to the increase of forest carbon storage in China.
This paper discusses the proximate and ultimate analysis of the test material what are four kinds of biomass in northern China. The results as shown in Table 1.2.2 The experimental apparatus and methodsAccording to the requirement of the biomass reburning denitration experiments, the experimental design of fixed bed reactor system is shown in Figure 1.
Abstract The phosphorus (P) forms in long‐term fertilization determine the fate and transport of P in soil. However, the fate of various pools of organic P of added P in the long‐term measured with sequential chemical fractionation is not well‐understood. Four soil physical aggregates (>250, 125–250, 63–125 and <63 μm) from 0‐ to 20‐cm depth after 35 years of long‐term fertilization treatments including control (CK), nitrogen and phosphorus fertilizer (NP) and NP combined with farmyard manure (NPM) under continuous winter wheat were separated using settling tube apparatus. Results showed that the application of long‐term P fertilization had no apparent effects on promoting the mass proportion of soil aggregates except for >250 μm, where the NP and NPM treatments significantly increased the mass proportion by 60% and 70% over CK, respectively. Compared with CK, P fertilizer (NP and NPM) treatments significantly increased organic P (Po) contents in each size aggregate. In particular, mean labile Po increased by 35% and 246%, moderately labile Po by 125% and 161%, nonlabile Po by 105% and 170% and total Po (TPo) by 101% and 178%, respectively, under NP and NPM treatments, respectively. There was a significant correlation between soil organic carbon (SOC) and Po fractions. SOC was exponentially positively correlated with labile Po but linearly positively correlated with moderately labile Po, nonlabile Po and TPo fractions among soil aggregates. A reduced C:Po ratio (<100) in soil aggregates among treatment indicates a large amount of available P accumulated in soils, and soil P loss risk in the study site is still high. Our results show that the Po pool measured by sequential chemical fractionation may represent an important, yet often overlooked, source of P in agriculture ecosystems. According to the result, long‐term mineral P fertilizer combined with organic amendments better sustains soil structural stability in large aggregates, contributing more Po availability in the moderately labile P followed by labile P in soil aggregates.
A 17 year field experiment,located at Yangling,Shaanxi,was conducted to study effects of different fertilizer managements on changes of microbial biomass carbon and nitrogen(SMBC,SMBN) and mineral nitrogen in soils under the winter wheat and summer maize rotation system.There were 4 fertilizer managements,no fertilization(CK),mineral N,P,and K fertilizers(F),mineral N,P,and K fertilizers and manure(F+M),and mineral N,P,and K fertilizers and straw (F+S).The results show that contents of SMBC,SMBN and soil mineral nitrogen are 264.8-752.2,37.5-114.8 and 3.8-38.5 mg/kg in the 010 cm soil layer,respectively.Contents of SMBC and SMBN in the F+M treatment are the highest among the different fertilizer treatments,and contents of SMBC and SMBN in the F+M treatment are 1.38-2.65 and 1.89-2.50 times of those in the no fertilizer treatment,respectively.Contents of soil mineral nitrogen of the F+S treatment are the highest among the different fertilizer treatments,and contents of SMBC,SMBN of the F+S treatment are higher than those of the F and CK treatments at all sampling times.Compared with the CK treatment,long-term application of mineral N,P,and K fertilizers increase SMBC and SMBN contents of 010 cm soil layer at every sampling time.SMBN contents in each fertilizer treatment from elongation stage to grain filling stage of winter wheat are decreased;however,soil mineral nitrogen contents are very low during this period.Soil mineral nitrogen contents in the F,F+M,and F+S treatments from pre-tasselling to grain filling stages of summer maize are decreased sharply,while,SMBN contents are increased.It is concluded that if there is enough mineral nitrogen in soil,crop would absorb it firstly,while if mineral nitrogen is limited,SMBN would be decomposed for crop uptake.
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