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It is critical to understand how farming practices affect the carbon and nitrogen footprints of agricultural production. Grain yield, economic return, and carbon and nitrogen footprints of spring wheat (Triticum aestivum L.) were examined under different tillage-mulch practices. Wheat was grown over 15 years (2002–2016) in the semi-arid region of the western Loess Plateau of China under six tillage-mulch practices: traditional plough with no straw mulching (T), no-till without straw mulching (NT), traditional plough with straw mulching (TS), no-till without straw mulching (NTS), traditional plough with plastic mulching (TP), no-till with plastic mulching (NTP). Average wheat yield over 15 years under NTS, NTP, TP and TS was increased by 28, 24, 22, and 13%, respectively, compared to T. Average net return was greatest under NTS and lowest under TP. The soils under all six tillage-mulch practices gained a considerably large amount of soil organic carbon (SOC) over the 15 yr. The increase in SOC in the 0–30 cm soil layer was greatest under NTS and lowest under T. When changes in soil C were included in the calculations, treatments of NT, TS, NTS, and NTP sharply reduced total greenhouse gas (GHG) emission compared to T. Compared to T, the carbon footprint was decreased by 180, 44, and 123% under NTS, NT, and TS, respectively, but was increased by 153% under TP. Compared to T, the nitrogen footprint was 24–26% lower in TP and NTP, but was not significantly different under NTS, NT, and TS. Therefore, NTS enhanced yield and net return, and reduced GHG and the carbon footprint without increasing the nitrogen footprint, and should be adopted to mitigate the environmental impacts of wheat production in the semiarid Loess Plateau.

Water availability is a major constraint for crop production in the Loess Plateau of China; thus, improving water use efficiency (WUE) is a main research target. The impact of alfalfa (Medicago sativa L.) growing age on forage yield, WUE, soil water storage, and soil fertility were examined in a 15-yr study in the western Loess Plateau of China. The results of this study indicate that long-term continuous production of alfalfa aggravated the soil water deficit and reduced soil available phosphorus (AP) and the ratio of soil organic carbon to soil total nitrogen, but increased soil organic carbon, soil total nitrogen, and the ratios of soil organic carbon to soil available phosphorus and soil total nitrogen to soil total phosphorus. After the ninth year of alfalfa production, the greatest soil water storage deficit degree was found in the 0–80 cm soil layer (63 %), followed by the 200–300 (57 %) and 80–200 cm (55 %) soil layers. Forage yield and WUE of alfalfa reached their greatest values following six- to nine-yr-old stands, and then decreased gradually. These results suggest that the yield decline with long-term stands of alfalfa may be related to reductions in soil water storage and AP, and their interaction, and the optimal alfalfa growing age should not extend beyond nine years in semiarid conditions.

After widespread application of the fully mulched ridge-furrow system, maize (Zea mays L.) has become a newly dominant crop in the semiarid Loess Plateau of China. Maximization of water use efficiency (WUE) through optimal farming practice are of great importance for sustainable intensification of maize production in this region. In this study, the impact of different tillage practices on soil quality, soil water, grain yield, WUE, and net economic return in a fully mulched ridge-furrow system were examined in a five-year field experiment, to optimize tillage practice for maize production in the area. Four tillage practices (CT, conventional tillage; NT, no-tillage; RT, rotary tillage; SS, subsoiling) were assessed. Compared to CT, SS reduced soil bulk density and penetration resistance, and increased saturated hydraulic conductivity and the percentage of macro-aggregates (≥ 0.25 mm) in the 0–30 cm soil layers, but NT and RT had the opposite effects to above soil physical properties except for macro-aggregates. Tillage practice did not significantly affect soil water storage, evapotranspiration, but annual soil water balance was lowest under SS, followed by CT, NT, and RT. SS increased soil organic C, mineral N and available P at 0−30 cm soil layer compared to CT. Grain yield and WUE under SS were increased by 12 and 15 % compared to CT, NT and RT had no significant effect on grain yield and WUE. Net economic return under NT and SS were increased by 42 and 23 % respectively compare to CT. These results demonstrated that subsoiling could improve grain yield, WUE, and net economic return of dryland maize by improving soil quality and mitigating soil water depletion. In the long-run, although no-tillage increased net economic return, it may not be sufficient to maintain yield and WUE due to deteriorated soil properties and accelerated soil water depletion. Thereby, subsoiling is optimal tillage practice for sustainable intensification of maize production in the semiarid Loess Plateau of China.

Drought is a major limiting factor for rainfed spring wheat production on the semiarid Loess Plateau of China. Suitable tillage practices are important for improving precipitation use efficiency (PUE), which is the ratio of grain yield to annual precipitation. To obtain a better understanding of the effects of conservation tillage practices on PUE on the semiarid Loess Plateau, PUE was divided into five steps: precipitation storage efficiency, farmland water consumption rate, ratio of transpiration to evapotranspiration, crop transpiration efficiency, and harvest index. Six tillage practices were assessed in this paper, including conventional tillage with no straw (T), no-till with straw cover (NTS), no-till with no straw (NT), conventional tillage with straw incorporated (TS), conventional tillage with plastic mulch (TP), and no-till with plastic mulch (NTP), based on a long-term experiment initiated in 2001. The impact of tillage practices on soil quality, soil water storage, soil evaporation, biomass yield, and grain yield of spring wheat were monitored in 2015 and 2016. The results show that NTS improved soil quality and soil water storage before sowing. No-till with plastic mulch and NTS increased evapotranspiration but decreased evaporation, thus optimizing precipitation storage efficiency, the farmland water consumption rate, the ratio of transpiration to evapotranspiration, and crop transpiration efficiency, which gave rise to greater aboveground dry matter accumulation and more dry matter accumulation in grain. As a result, grain yield under NTS and NTP was significantly increased by 45 and 41 % compare to T, respectively, with corresponding improvements in PUE of 43 and 39 %. Therefore, both NTS and NTP have potential to substantially increase grain yield of spring wheat and PUE. However, for sustainable intensification in the long-run, NTS is the best combination of tillage and soil surface management for spring wheat production on the semi-arid Loess Plateau of China.

Nitrogen (N) application is a basic practice for increasing cereal yield and efficient utilization of N sources is key to sustainable intensification. A meta-analysis was conducted to determine how organic fertilization (i.e., livestock manure) affects yield, yield variability and water use efficiency (WUE) of winter wheat (Triticum aestivum L.) in northern China, and how this is impacted by N management and growing environment. Organic fertilization significantly increased grain yield and WUE by an average of 18 and 20 % compared to without organic fertilizer, respectively, and also reduced spatial and temporal yield variability. Compared to without organic fertilizer, change in grain yield was +24, +28, and −11 % for treatments of synthetic nitrogen fertilizer plus organic fertilizer with the same level of synthetic nitrogen (NOF), decreased level of synthetic nitrogen fertilizer combined with organic fertilizer (NLOF), and a portion of synthetic nitrogen fertilizer replaced with organic nitrogen fertilizer at the same level of nitrogen (NROF), respectively. The positive effect of organic fertilizer on grain yield and WUE of winter wheat was greatest when yield levels was