Organic amendments increase corn yield by enhancing soil resilience to climate change

A 22-year field experiment was conducted in Gongzhuling, Jilin province, China to investigate corn yield response to fertilization practice. Compared to an unfertilized control(CK), all fertilization treatments, including inorganic nitrogen fertilizer only(N), balanced inorganic fertilizers(NPK), NPK plus corn straw(SNPK), and NPK plus farmyard manure(MNPK), resulted in significant increases in corn yield. However, only organic matter amendments sustained increasing yield trends, with annual rates of 0.137 and 0.194 t ha-1for the SPNK and MNPK treatments, respectively(P < 0.05). During the 22 years, the daily mean, maximum and minimum temperatures increased by 0.50, 0.53, and 0.46 °C per decade, whereas precipitation displayed no significant change but showed large seasonal variation. According to a regression analysis, increased air temperature exerted positive effects on corn yields under the SNPK and the MNPK treatments. Under both treatments,soil organic carbon contents and soil nutrient availabilities increased significantly compared to their initial levels in 1990, whereas soil bulk density and total porosity changed slightly under the two treatments, which showed higher soil water storage than other treatments. In contrast, significant increases in soil bulk density and decreases in soil total porosity and soil nutrient availability were observed under the CK, N and NPK treatments. The contributions of soil fertility to corn yield were 28.4%, 37.9%, 38.4%, 39.0%,and 42.9% under CK, N, NPK, SNPK, and MNPK treatments, respectively, whereas climate changes accounted for 27.0%, 14.6%, 12.4%, 11.8%, and 10.8%. These results indicate that, in Northeast China, organic matter amendments can mitigate negative and exploit positive effects of climate change on crop production by enhancing soil quality.

Impacts of Nighttime Warming on the Soil Nematode Community in a Winter Wheat Field of Yangtze Delta Plain, China

Changes in the soil nematode community induced by global warming may have a considerable influence on agro-ecosystem functioning. However, the impacts of predicted warming on nematode community in farmland （e.g., winter wheat field） have not been well documented. Therefore, a field experiment with free air temperature increase （FATI） was conducted to investigate the responses of the soil nematode community to nighttime warming in a winter wheat field of Yangtze Delta Plain, China, during 2007 to 2009. Nighttime warming （NW） by 1.8~C at 5-cm soil depth had no significant impact on the total nematode abundance compared to un-warmed control （CK）. However, NW significantly affected the nematode community structure. Warming favored the bacterivores and fungivores, such as Acrobeles, Monhystera, Rhabditis, and Rhabdontolaimus in bacterivores, and Filenchus in fungivores, while the plant-parasites were hindered, such as Helicotylenchus and Psilenchus. Interestingly, the carnivores/ omnivores remained almost unchanged. Hence, the abundances ofbacterivores and fungivores were significantly higher under NW than those under CK. Similarly, the abundances of plant-parasites were significantly lower under NW than under CK. Furthermore, Wasilewska index of the nematode community was significantly higher under NW than those under CK, indicating beneficial effect to the plant in the soil. Our results suggest that nighttime warming may improve soil fertility and decrease soil- borne diseases in winter wheat field through affecting the soil nematode community. It is also indicated that nighttime warming may promote the sustainability of the nematode community by altering genera-specific habitat suitability for soil biota.