Quinoa (Chenopodium quinoa Willd.) yield potential needs to be further achieved by good management practices to meet the increasing global demand. Two years of orthogonal field experiments were undertaken to investigate the effects of irrigation onset criteria using soil matric potential (SMP) (−15, −25, and −55 kPa), nitrogen fertilizer rate (80, 160, and 240 kg ha−1), and plant density (20, 30, and 40 plants m−2) on quinoa growth, seed yield, weight, and protein content. Initiating irrigations at an SMP of −15 to −25 kPa achieved significantly (p < 0.05) greater seed yield (37.2 g plant−1), thousand kernel weight (2.25 g), and protein content (21.2%) than −55 kPa (25.2 g plant−1, 2.08 g, and 19.8%, respectively). The 240 kg ha−1 nitrogen rate had significantly (p < 0.05) greater thousand kernel weight (2.26 g) and protein content (21.3%) than 80 (2.07 g and 19.5%, respectively) and 160 kg ha−1 (2.14 g and 20.7%, respectively). The yield under 20 plants m−2 reached 39.5 g plant−1, which was 13.5 g plant−1 higher than 40 plants m−2 (p < 0.05). The quinoa consumed most of the available nitrogen in the soil (410–860 kg ha−1), indicating that quinoa should be part of a sound crop rotation program.

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Using manure in potato production has been considered for its potential environmentally friendly effects. Two years of field experiments were conducted to evaluate the effects of different kinds of fertilizer and soil surface treatments on potato growth. Experimental treatments consisted of three soil surface treatments, including black plastic-film mulch (BM), transparent film-plastic mulch (TM), and non-mulched (NM) treatment, and two fertilizer treatments, including inorganic fertilizer (IF), and cattle manure (CM). The results showed that low environmental temperatures at early growth stages harmed potato growth. The more suitable hydrothermal environment under BM treatment induced 9–67%, 1–223%, 15–30%, −1–11% and 18–34% greater plant height, leaf area index (LAI), tuber yield, crop evapotranspiration (ETc) and water use efficiency (WUE), respectively, than NM and TM treatments. Plastic-film mulch increased soil carbon dioxide concentration, especially for the TM treatment. With low soil nitrogen content during the whole growth stage, and high soil carbon dioxide concentration during sprout and seedling stages, the CM treatment reduced plant height, LAI, tuber yields, ETc and WUE by 27–155%, 2–96%, 6–23%, 2–6% and 8–25%, respectively. These results suggest that inorganic fertilizer with black plastic-film mulch is still the best choice for potato production, and further studies are needed to identify the best level of cattle manure used under black plastic-film mulch.

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Black plastic film mulching is a common practice for potato production in the arid area of Northwest China. Many studies have reported the significant positive effect of black plastic film mulch on potato harvest, while the effect of black plastic film mulch treatment on soil nitrous oxide (N2O) emissions is still unclear. As a consequence, this study aimed to examine the effect of black plastic film mulch treatment on N2O emission from arid upland potato fields. With the static chamber-gas chromatography method, soil N2O emissions were measured. The results showed that black plastic film mulching treatment significantly increased cumulative soil N2O emissions by 21–26% compared with non-mulched treatment. Cumulative N2O emission positively correlated with soil temperature, soil moisture, soil CO2 concentration, and amoA-AOB abundance. This study indicated that black plastic film mulching, mainly through increasing soil temperature and soil moisture, increasing soil carbon dioxide (CO2) concentration, and promoting the abundance of nitrification-related functional gene of amoA-AOB, regulated N2O emissions. This study also highlighted that the specific soil environment under black plastic film mulch is conducive to N2O emissions and lay the foundation for settling the contradiction between food production and greenhouse gas mitigation in upland soils. The negative effects of black plastic film mulching on the environment should be considered in future applications in food production.