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Aims and background: Soil fertility quality index is a useful indicator that helps to improve sustainable land use management and achieve economical yield in agriculture production. The objectives of this study were to evaluate the changes of soil fertility quality between the 1980s and 2000s in different cropping systems and its significance to crop productivity and sustainability. Methods: We collected all published data on crop yields and soil parameters from 58 long-term experiments in three typical double-cropping systems in China, including maize-wheat (M-W), rice-rice (R-R) and rice-wheat (R-W) cropping systems, and selected seven fertilizer treatments in each experiment, including inorganic fertilizer [nitrogen and phosphorus fertilizer (NP), nitrogen and potassium fertilizer (NK), phosphorus and potassium fertilizer (PK) and balanced mineral fertilizer (NPK)], combined NPK with farmyard manure (NPKM) or crop straw (NPKS), and no fertilizer application (served as control). For comparison, an integrated fertility quality index (IFQI) was used to estimate the variations in soil fertility in different cropping systems. Moreover, the mean production variability index (PVI, %) in each cropping system was calculated to evaluate the stability of crop production. Results: Over cropping systems, the averaged relative yields of PK, NK and NP ranged from 38.0 to 97.4 %, while the mean yields can be increased by 2.4-5.1 % in NPKM, compared to NPK. The mean yields were similar between NPK and NPKS for maize and wheat crops, but the yield was increased by 4.3-10.0 % in NPKS. Among the different treatments, the highest variability of cereal productivity was obtained in NK, PK or Control, while the lowest value was mostly recorded in NPKM or NPKS in these three cropping systems. Relative to the control, the IFQIs in fertilization treatments were increased by 9.4-150.0 %, 6.2-41.5 % and 1.3-17.5 % in M-W, R-W and R-R systems, respectively (except for PK treatment in R-R system). However, changes of IFQI in topsoil differed among fertilizer treatments, and greater increases existed in the treatments receiving organic residues (NPKM and NPKS). Conclusions: The increase in crop yield is exponentially correlated with the increased IFQI over treatments in three cropping systems. Over the treatments and systems, production variability among years is shown to be negatively, linearly related to IFQI ( P < 0.001). Therefore, the high grain yield and low production variability can be simultaneously achieved by increasing soil fertility in all three cropping systems. [ABSTRACT FROM AUTHOR]

Abstract: Fertilization plays a pivotal role on soil biological process and affects the soil bacterial community, which act as hosts for viruses. The effect of fertilization on soil viral community has not been well explored. In this study, a Haplic Acrisol soil, which is the soil type for 13 provinces in Southern China, was analyzed after 22 years different fertilization regimes for their viral composition. The soil responded to organic fertilizations with an increased amount of soil organic matter (SOM) and pH (increased from 5.7 to 6.6), while with the decreased SOM and pH for chemical fertilization, especially for single nitrogen fertilization. The combined effects of SOM and pH caused by long-term different fertilization regimes on soil viral communities were investigated by direct calculation of virus-like particles (VLPs) through epifluorescence microscopy. The highest VLP abundance (13.1 × 107 per gram dry soil) was detected in soil applied with chemical and organic fertilizers. The viral and bacterial abundances of organic soil were 4 and 5 times higher than those of inorganic soil respectively. Transmission electron microscopy observation revealed a higher frequency of Myoviridae viruses in soil with organic amendments than without organic amendments, and vice versa for Podoviridae viruses. These results demonstrate that organic fertilizer could increase viral abundance and morphological diversity through suppressing soil acidification and improving soil organic matter. [Copyright &y& Elsevier]