Phosphorus (P) is a finite natural resource and is increasingly considered to be a challenge for global sustainability. Agriculture in China plays a key role in global sustainable P management. Rhizosphere and soil-based P management are necessary for improving P-use efficiency and crop productivity in intensive agriculture in China. A previous study has shown that the future demand for phosphate fertilizer by China estimated by the LePA model (legacy phosphorus assessment model) can be greatly reduced by soil-based P management (the building-up and maintenance approach). The present study used the LePA model to predict the phosphate demand by China through combined rhizosphere and soil-based P management at county scale under four P fertilizer scenarios: (1) same P application rate as in 2012; (2) rate maintained same as 2012 in low-P counties or no P fertilizer applied in high-P counties until targeted soil Olsen-P (TPOlsen) level is reached, and then rate was the same as P-removed at harvest; (3) rate in each county decreased to 1–7 kg ha^–1 yr^–1 after TPOlsen is reached in low-P counties, then increased by 0.1–9 kg ha^–1 yr^–1 until equal to P-removal; (4) rate maintained same as 2012 in low-P counties until TPOlsen is reached and then equaled to P-removal, while the rate in high-P counties is decreased to 1–7 kg ha^–1 yr^–1 until TPOlsen is reached and then increased by 0.1–9 kg ha^–1 yr^–1 until equal to P-removal. Our predictions showed that the total demand for P fertilizer by whole China was 693 Mt P2O5 and according to scenario 4, P fertilizer could be reduced by 57.5% compared with farmer current practice, during the period 2013–2080. The model showed that rhizosphere P management led to a further 8.0% decrease in P fertilizer use compared with soil-based P management. The average soil Olsen-P level in China only needs to be maintained at 17 mg kg^–1 to achieve high crop yields. Our results provide a firm basis for government to issue-relevant policies for sustainable P management in China.

Caprine arthritis-encephalitis virus (CAEV) is an under-studied virus infecting caprines and ovines worldwide.  Over the last four decades, CAEV has spread in China, obtaining genomic data on CAEV strains circulating in China is of importance for developing diagnostic methods and eradicating associated diseases.  However, there is limited information on the genome, including characterizations, and the probable origin.  This work aimed to characterize Chinese CAEV genomes and population structures.  Five CAEV strains isolated from infected dairy goats between 1989 and 1994 in Gansu, Guizhou, Shaanxi, Shandong and Sichuan provinces were cloned and sequenced.  The Chinese CAEV had a 58–93% genome similarities to strains outside of China, and they belonged to subgenotype B1.  The highest similarity levels (98.3–99.3%) were with two other Chinese strains, and they shared a 91.8–92.3% similarity with the strain Clements (GenBank accession no. NC_001463.1) from outside of China.  The Chinese CAEV strains isolated from different provinces over five years were still highly homologous and contained unique ancestral population components, indicating that these Chinese strains had a common origin that differed from other known strains.  Our results provide genomic data on circulating Chinese CAEV strains and will be useful for future epidemiological investigations and CAEV eradication programs.

Understanding the characteristics and influences of various factors on phosphorus (P) fractions is of significance for promoting the efficiency of soil P.  Based on long-term experiments on black soil, fluvo-aquic soil, and loess soil, which belong to Phaeozems, Cambisols, and Anthrosols in the World Reference Base for Soil Resources (WRB), respectively, five fertilization practices were selected and divided into three groups: no P fertilizer (CK/NK), balanced fertilizer (NPK/NPKS), and manure plus mineral fertilizer (NPKM).  Soil inorganic P (Pi) fractions and soil properties were analyzed to investigate the characteristics of the Pi fractions and the relationships between Pi fractions and various soil properties.  The results showed that the proportion of Ca₁₀-P in the sum of total Pi fractions was the highest in the three soils, accounting for 33.5% in black soil, 48.8% in fluvo-aquic soil, and 44.8% in loess soil.  Long-term fertilization practices resulted in periodic changes in soil Pi accumulation or depletion.  For black soil and fluvo-aquic soil, the Pi accumulation was higher in the late period (10–20 years) of fertilization than in the early period (0–10 years) under NPK/NPKS and NPKM, whereas the opposite result was found in loess soil.  The Pi accumulation occurred in all Pi fractions in black soil; mainly in Ca₈-P, Fe-P, and Ca₁₀-P in fluvo-aquic soil; and in Ca₂-P, Ca₈-P, and O-P in loess soil.  Under CK/NK, the soil Pi was depleted mainly in the early period in each of the three soils.  In addition to the labile Pi (Ca₂-P) and moderately labile Pi (Ca₈-P, Fe-P, Al-P), the Ca₁₀-P in black soil and fluvo-aquic soil and O-P in loess soil could also be used by crops.  Redundancy analysis showed that soil properties explained more than 90% of the variation in the Pi fractions in each soil, and the explanatory percentages of soil organic matter (SOM) were 43.6% in black soil, 74.6% in fluvo-aquic, and 38.2% in loess soil.  Consequently, decisions regarding the application of P fertilizer should consider the accumulation rate and the variations in Pi fractions driven by soil properties in non-acidic soils.

This study investigated the effects of three contrasting soil management regimes and different nutrient treatments on the distribution of water-stable aggregates (>2, 1–2, 0.5–1, 0.25–0.5, and <0.25 mm) and associated soil organic carbon (SOC) and total nitrogen (TN) content in loess soil. A 21-yr long-term experiment was performed, in which soil management regimes include cropland abandonment (Abandonment), bare fallow (Fallow) and wheat-fallow cropping (Cropping). Under Cropping, the following nutrient treatments were employed: control (CK, no nutrient input), nitrogen only (N), nitrogen and potassium (NK), phosphorus and potassium (PK), NP, NPK, and manure (M) plus NPK (MNPK). Results demonstrated that Abandonment significantly increased the content of soil macro-aggregates (>0.25 mm) and mean weight diameter (MWD) at 0–10 and 10–20 cm soil horizons compared with Cropping, whereas Fallow yielded lower values of above two parameters. Abandonment increased SOC and TN contents in all aggregate sizes by 17–62% and 6–60%, respectively, at 0–10 cm soil layer compared with Cropping. Conversely, Fallow decreased SOC and TN contents in all aggregates by 7–27% and 7–25%, respectively. Nevertheless, the three soil management regimes presented similar SOC contents in all aggregates at 10–20 cm soil horizon. Only Cropping showed higher TN content in >0.5 mm aggregates than the two other regimes. Consequently, Abandonment enhanced the partitioning proportions of SOC and TN in >1 mm macro-aggregates, and Fallow promoted these proportions in micro-aggregates compared with Cropping. Under Cropping, long-term fertilization did not affect the distribution of aggregates and MWD values compared with those under CK, except for NPK treatment. Fertilizer treatments enhanced SOC and TN contents in aggregates at all tested soil depths. However, fertilization did not affect the partitioning proportions of SOC and TN contents in all aggregates compared with CK. Comprehensive results showed that different soil management regimes generated varied patterns of SOC and TN sequestration in loess soil. Abandonment enhanced soil aggregation and sequestered high amounts of SOC and TN in macro-aggregates. Long-term amendment of organic manure integrated with NPK maintained soil aggregate stability and improved SOC and TN sequestration in all aggregates in loess soil subjected to dryland farming.

The sustainability of the wheat-maize rotation is important to China’s food security. Intensive cropping without recycling crop residues or other organic inputs results in the loss of soil organic matter (SOM) and nutrients, and is assumed to be non- sustainable. We evaluated the effects of nine different treatments on yields, nitrogen use efficiency, P and K balances, and soil fertility in a wheat-maize rotation system (1991-2010) on silt clay loam in Shaanxi, China. The treatments involved the application of recommended dose of nitrogen (N), nitrogen and phosphorus (NP), nitrogen and potassium (NK), phosphorus and potassium (PK), combined NPK, wheat or maize straw (S) with NPK (SNPK), or dairy manure (M) with NPK (M1NPK and M2NPK), along with an un-treated control treatment (CK). The mean yields of wheat and maize ranged from 992 and 2 235 kg ha-1 under CK to 5 962 and 6 894 kg ha-1 under M2NPK treatment, respectively. Treatments in which either N or P was omitted (N, NK and PK) gave significantly lower crop yields than those in which both were applied. The crop yields obtained under NP, NPK and SNPK treatments were statistically identical, as were those obtained under SNPK and MNPK. However, M2NPK gave a significant higher wheat yield than NP, and MNPK gave significant higher maize yield than both NP and NPK. Wheat yields increased significantly (by 86 to 155 kg ha-1 yr-1) in treatments where NP was applied, but maize yields did not. In general, the nitrogen use efficiency of wheat was the highest under the NP and NPK treatments; for maize, it was the highest under MNPK treatment. The P balance was highly positive under MNPK treatment, increasing by 136 to 213 kg ha-1 annually. While the K balance was negative in most treatments, ranging from 31 to 217 kg ha-1 yr-1, levels of soil available K remained unchanged or increased over the 20 yr. SOM levels increased significantly in all treatments. Overall, the results indicated that combinations of organic manure and inorganic nitrogen, or returning straw with NP is likely to improve soil fertility, increasing the yields achievable with wheat-maize system in a way which is environmentally and agronomically beneficial on the tested soil.

The presence of abundant and diverse communities of macro-arthropods is considered an indicator of sustainability in agroecosystems. This study was designed to investigate the effects of different fertilizer treatments on abundance and diversity of insects of arable loess soil on the Loess Plateau of China. These regimes included a control with no fertilizer addition or manure, treatments with application of mineral fertilizers (N, NK, NP, PK, NPK), treatments with NPK in combination with organic materials such as wheat straw or maize stalk, treatments with two rates of organic manure application; and different crop rotations (Rot.1: winter wheat summer maize; Rot.2: winter wheat summer maize soybean intercropping; and Rot.3: winter wheat or rapeseed summer maize soybean intercropping). Soil macro-arthropods were collected from the plough layer (0-20 cm) and sorted by hand after each harvest in June and October 2001 and 2002. A total of 3 132 individuals were collected, from 7 orders and 55 families, dominated by Formicidae (61.72%) and Staphylinidae (14.24%). The results showed that individuals and groups were significantly influenced by sampling dates, while groups were significantly influenced by the fertilization treatments. Soil insect biodiversity, as determined by the Shannon index, was significantly influenced by fertilization and sampling dates. The abundance of soil insects was positively and significantly correlated with soil moisture content in October 2002. Nitrogen, phosphorus and potassium fertilizers and incorporation of organic materials were favorable factors for abundance and diversity in arable loess soil.