Unreasonable fertilization often fails to match crop yield and nutrient requirements, leading to low crop yield, the waste of mineral resources, and increased costs for farmers. A survey of the potato yield and fertilization of farmers was conducted in Haidong City of Qinghai Province for three consecutive years (2017–2019) torecommend reasonable fertilizer application. The results showed that the required amount of NPK fertilizer per ton of potato was 4.85 kg N, 1.26 kg P₂O₅, and 6.98 kg K₂O, respectively. The potato yields ranged from 7500 to 66,429 kg ha⁻¹, with an average of 26,069 kg ha⁻¹. The average N, P, and Kfertilizers (in the form of N, P₂O_5, and K₂O, respectively) applied by the farmers were 213 kg N ha⁻¹, 202 kg P₂O₅ha⁻¹, and 43 kg K₂O ha⁻¹. More than 60% of the farmers appliedtoo much Nand Pfertilizers and too little Kfertilizer. Therefore, the farmers with lowyieldsshould reduce the application of Nand P fertilizers by a range of 41–220 kg ha⁻¹ and 24–265 kg ha⁻¹. Allthe farmers should increase Kfertilizer use by 7–273 kg ha⁻¹. Reasonable fertilization could effectively conserve resources, improve economic efficiency, and reduce environmental impact.

Wolfberry production has become a major agro-industry on the Qinghai–Tibetan Plateau, causing increased nitrogen (N) pollution and greenhouse gas (GHG) emissions. Appropriate N fertilizer rate and nitrification inhibitors may mitigate GHG emissions and improve N use efficiency. A 2-year field experiment was conducted to measure the effects of N application rate and nitrapyrin on GHG emissions, to reduce GHG emissions and N pollution. We used eight treatments: Control (CK), 667 kg·ha⁻¹ N (Con), 400 kg·ha⁻¹ N (N₄₀₀), 267 kg·ha⁻¹ N (N₂₆₇), 133 kg·ha⁻¹ N (N₁₃₃), 400 kg·ha⁻¹ N plus 2.00 kg·ha⁻¹ nitrapyrin (N₄₀₀I_2.00), 267 kg·ha⁻¹ N plus 1.33 kg·ha⁻¹ nitrapyrin (N₂₆₇I_1.33) and 133 kg·ha⁻¹ N plus 0.67 kg·ha⁻¹ nitrapyrin (N₁₃₃I_0.67). Compared with Con treatment, N₄₀₀ maintained fruit yield and increased net income, but saved 40% of N fertilizer and decreased the cumulative N₂O emission by 14–16%. Compared to N₄₀₀, N₂₆₇ and N₁₃₃ treatments, the cumulative N₂O emission of N₄₀₀I_2.00, N₂₆₇I_1.33 and N₁₃₃I_0.67 treatments was reduced by 28.5–45.1%, 26.6–29.9% and 33.8–45.9%, respectively. Furthermore, N₄₀₀I_2.00 resulted in the highest wolfberry yield and net income. The emissions of CH₄ and CO₂ were not significantly different among treatments. Moreover, the global warming potential (GWP) and the greenhouse gas emission intensity (GHGI) of N₄₀₀I_2.00 declined by 45.6% and 48.6% compared to Con treatment. Therefore, 400 kg·ha⁻¹ N combined with 2.00 kg·ha⁻¹ nitrapyrin was shown to be a promising management technique for maintaining wolfberry yield while minimizing GWP and GHGI.

Imbalanced fertilization and inadequate of straw return have led to soil potassium (K) depletion and fertility decline in croplands of the Qinghai–Tibet Plateau. However, how these changes affect soil microbial communities remains unclear. We analyzed soil properties, microbial biomass carbon and nitrogen, enzyme activities, and microbial communities in a long-term field experiment initiated in 1992 with K fertilization and varying wheat straw return amounts. Long-term K application significantly reduced microbial biomass carbon (MBC) and bacterial species richness and inhibited positive bacteria–fungi interactions. By contrast, long-term straw return not only enhanced soil organic carbon (SOC), total nitrogen (TN), available phosphorus (AP), and available potassium (AK) but also increased MBC, microbial biomass nitrogen (MBN), enzyme activities, and fungal species richness. Furthermore, it restructured microbial community composition and improved the stability and connectivity of microbial co-occurrence networks. Critically, these benefits did not scale linearly with straw input quantity. Excessive straw return (>5000 kg ha⁻¹) reduced beneficial effects, destabilized microbial interactions, and elevated risks associated with parasitic protozoa. Balanced potassium application with moderate straw return (approximately 5000 kg ha⁻¹) enhances soil fertility and promotes positive microbial effects in croplands on the Qinghai–Tibet Plateau.

(1) Background: This study aimed to evaluate the effects of organic fertilizer dose on soil nutrients, wolfberry fruit nutrient compositions, and fruit yields. (2) Methods: We conducted a two-year field trial in two typical fields with different fertility levels in the Qaidam area. Six treatments were applied to each field, including CK, M2 M4, M6, M8, and M10 (representing 0, 2, 4, 6, 8, and 10 kg organic fertilizer/plant, respectively) in the high-fertility field and CK, M3, M6, M9, M12, and M15 (representing 0, 3, 6, 9, 12, and 15 kg organic fertilizer/plant, respectively) in the low-fertility field. An ANOVA was used to determine the significant difference between treatments, and the LSD method was used for multiple comparisons of analysis of variance. (3) Results: In the high-fertility field, the application of organic fertilizer significantly affected the total nitrogen (N) content, mineral N storage, and soil organic matter content. The application of too much organic fertilizer significantly increased the soil’s EC value. In the low-fertility field, the effect of organic fertilizer application on soil nutrient enhancement differed significantly among soil layers but significantly increased the contents of total phenols, flavonoids, and amino acids in wolfberry fruit, and there was a significant trend of increasing wolfberry yield with increasing organic fertilizer application. (4) Conclusions: In the Qaidam area of the Tibetan Plateau, it is recommended to apply 2–4 kg commercial organic fertilizer/plant in the high-fertility wolfberry orchards while 9–12 kg in the low-fertility wolfberry orchards is recommended.