Search

• Integrated management of agronomic practices largely improved the wheat yield. • The high yield was due to the higher water use efficiency and subsoil water using. • The changing of water use patterns contributed to the higher water use efficiency. Low yields of winter wheat are common throughout the Loess Plateau due to the region's erratic precipitation and the mismatch between the rainy season and the winter wheat growing season. In order to achieve sustainable high yields of winter wheat in this area, we set 6,000 kg hm−2 as our yield goal and investigated the effects of four types of management systems, including a conventional farmers' management system and three integrated management systems, on winter wheat production over five consecutive years. The management practices varied in terms of seeding rates, nitrogen (N) application strategies, and application of manure or biochar. Our five-year study revealed that the average winter wheat yield under a manure integrated system (MIS) or a biochar integrated system (BIS) could achieve nearly 6,000 kg hm−2 while also enhancing water use efficiency (WUE) to 1.63–1.69 kg m−3. The high yields under MIS and BIS were mainly due to the large plant population that these systems permitted during the whole growing season, which was supported by favorable soil N levels (NO 3 −–N content) and sufficient water supply. The high WUE under both systems was mainly due to decreased loss of precipitation (i.e., increased storage in the soil) during early growth stages (from sowing time to regreening stage) and increased use of subsoil water (100–300 cm) during late growth stages (from regreening to harvest time) by the large root system. In addition, the annual evapotranspiration under MIS and BIS was much lower than the annual precipitation in this area. Therefore, MIS and BIS are likely to be useful integrated management systems enabling sustainable high yields of winter wheat in the Loess Plateau through the regulation of water use patterns in both spatial and temporal terms. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Converting natural forests to intensively managed plantations markedly alters soil carbon (C) dynamics. However, the impact of such land-use change on soil respiration (R S ) components remains unclear. The objective of this study was to examine the effect on R S , autotrophic respiration (R A ) and heterotrophic respiration (R H ) of converting a natural evergreen broadleaf forest to an intensively managed Moso bamboo ( Phyllostachys edulis ) plantation. A two-year field study was carried out to assess the seasonal dynamics of R S , R A and R H in three broadleaf forest-bamboo plantation pairs, using a portable soil CO 2 flux measurement system. Results showed that converting the evergreen broadleaf forest to the bamboo plantation increased the annual cumulative R S and R H by 18.8% and 20.9%, respectively, but did not change the annual cumulative R A . Soil temperature alone explained 48% and 79% of seasonal variations in R A and R H , respectively, in the evergreen broadleaf forest, and 68% and 79%, respectively, in the bamboo plantation. The land-use change increased the apparent temperature sensitivity ( Q 10 ) of R A , but did not affect that of R H . Regardless of the land-use type, both R A and R H were positively correlated with soil water soluble organic C, but not with soil moisture content. The R H was positively correlated to soil microbial biomass C (MBC) in the evergreen broadleaf forest, but not in the bamboo plantation. The R A was not correlated with soil MBC, regardless of the land-use type. Therefore, soil R A and R H responded differently to land-use change and variations in environmental factors, suggesting that partitioning of R S to different components is essential to elucidate mechanisms associated with changes in R S induced by land-use change and to predict R S under different climate change scenarios. [ABSTRACT FROM AUTHOR]