该研究系统阐述了长期不同施肥对土壤剖面SOC和N库的影响，通过冗余分析了SOC团聚体组分及影响因素，三维表面分析深入理解剖面SOC和N库对作物产量的影响。与化肥处理相比，长期施用有机肥通过增加表土层 (0–20 cm）SOC输入、SOC储量、TN储量和土壤pH值来提高作物产量。不同施肥处理的SOC团聚体组分存在差异，所有处理SOC团聚体组分高低依次为矿物结合有机碳（mSOC）>粗自由颗粒有机碳（cfPOC）>物理保护有机碳（iPOC）>细自由颗粒有机碳（ffPOC）。施用有机肥处理的所有SOC组分含量均显著高于化肥处理。在不同SOC团聚体组分中，ffPOC对不同施肥处理的敏感性最高。单施有机肥（M）和有机无机肥配施（NPKM）显著提高了表层（0-20 cm）SOC和TN含量，与化肥处理相比，M和NPKM处理降低了深层土壤（80-100 cm）中的SOC和N含量，有利于减少养分垂直流动，从而减少养分的淋溶损失。

Nitrogen (N) loss from fertilization in agricultural fields has an unavoidable negative impact on the environment and a better
understanding of the major pathways can assist in developing the best management practices. The aim of this study was
to evaluate the fate of N fertilizers applied to acidic red soil (Ferralic Cambisol) after 19 years of mineral (synthetic) and
manure fertilizer treatments under a cropping system with wheat-maize rotations. Five field treatments were examined:
control (CK), chemical nitrogen and potash fertilizer (NK), chemical nitrogen and phosphorus fertilizer (NP), chemical nitrogen,
phosphorus and potash fertilizer (NPK) and the NPK with manure (NPKM, 70% N from manure). Based on the soil
total N storage change in 0–100 cm depth, ammonia (NH3) volatilization, nitrous oxide (N₂O) emission, N plant uptake, and
the potential N leaching loss were estimated using a mass balance approach. In contrast to the NPKM, all mineral fertilizer
treatments (NK, NP and NPK) showed increased nitrate (NO₃^–-N) concentration with increasing soil depth, indicating higher
leaching potential. However, total NH3 volatilization loss was much higher in the NPKM (19.7%) than other mineral fertilizer
treatments (≤4.2%). The N₂O emissions were generally low (0.2–0.9%, the highest from the NPKM). Total gaseous loss
accounted for 1.7, 3.3, 5.1, and 21.9% for NK, NP, NPK, and NPKM treatments, respectively. Estimated N leaching loss
from the NPKM was only about 5% of the losses from mineral fertilizer treatments. All data demonstrated that manure
incorporation improved soil productivity, increased yield, and reduced potential leaching, but with significantly higher NH₃
volatilization, which could be reduced by improving the application method. This study confirms that manure incorporation is an essential strategy in N fertilization management in upland red soil cropping system.

Upland red soils have been identified as major CO2 and N2O sources induced by human activities such as fertilization. To monitor characteristics of soil surface CO2 and N2O fluxes in cropland ecosystems after continuous fertilizer applications over decades and to separate the respective contributions of root and heterotrophic respiration to the total soil CO2 and N2O fluxes, the measurements of soil surface CO2 and N2O fluxes throughout the maize growing season in 2009 were carried out based on a fertilization experiment (from 1990) through of the maize (Zea mays L.) growing season in red soil in southern China. Five fertilization treatments were chosen from the experiment for study: zero-fertilizer application (CK), nitrogen-phosphorus- potassium (NPK) fertilizer application only, pig manure (M), NPK plus pig manure (NPKM) and NPK with straw (NPKS). Six chambers were installed in each plot. Three of them are in the inter-row soil (NR) and the others are in the soil within the row (R). Each fertilizer treatment received the same amount of N (300 kg ha-1 yr-1). Results showed that cumulative soil CO2 fluxes in NR or R were both following the order: NPKS>M, NPKM>NPK>CK. The contributions of root respiration to soil CO2 fluxes was 40, 44, 50, 47 and 35% in CK, NPK, NPKM, M and NPKS treatments, respectively, with the mean value of 43%. Cumulative soil N2O fluxes in NR or R were both following the order: NPKS, NPKM>M>NPK>CK, and soil N2O fluxes in R were 18, 20 and 30% higher than that in NR in NPKM, M and NPKS treatments, respectively, but with no difference between NR and R in NPK treatment. Furthermore, combine with soil temperature at -5 cm depth and soil moisture (0-20 cm) together could explain 55-70% and 42-59% of soil CO2 and N2O emissions with root interference and 62- 78% and 44-63% of that without root interference, respectively. In addition, soil CO2 and N2O fluxes per unit yield in NPKM (0.55 and 0.10 kg C t-1) and M (0.65 and 0.13 g N t-1) treatments were lower than those in other treatments. Therefore, manure application could be a preferred fertilization strategy in red soils in South China.

A long-term field experiment was established to determine the influence of mineral fertilizer and organic manure on soil fertility. A tract of red soil (Ferralic Cambisol) in Qiyang Red Soil Experimental Station (Qiyang County, Hunan Province, China) was fertilized beginning in 1990 and N2O and CO2 were examined during the maize and wheat growth season of 2007-2008. The study involved five treatments: organic manure (NPKM), fertilizer NPK (NPK), fertilizer NP (NP), fertilizer NK (NK), and control (CK). Manured soils had higher crop biomass, organic C, and pH than soils receiving the various mineralized fertilizers indicating that long-term application of manures could efficiently prevent red soil acidification and increase crop productivity. The application of manures and fertilizers at a rate of 300 kg N ha-1 yr-1 obviously increased N2O and CO2 emissions from 0.58 kg N2O-N ha-1 yr-1 and 10 565 kg C ha-1 yr-1 in the CK treatment soil to 3.01 kg N2O-N ha-1 yr-1 and 28 663 kg C ha-1 yr-1 in the NPKM treatment. There were also obvious different effects on N2O and CO2 emissions between applying fertilizer and manure. More N2O and CO2 released during the 184-d maize growing season than the 125- d wheat growth season in the manure fertilized soils but not in mineral fertilizer treatments. N2O emission was significantly affected by soil moisture only during the wheat growing season, and CO2 emission was affected by soil temperature only in CK and NP treatment during the wheat and maize growing season. In sum, this study indicates the application of organic manure may be a preferred strategy for maintaining red soil productivity, but may result in greater N2O and CO2 emissions than treatments only with mineral fertilizer.