78 IPNI Interpretive Summaries
Asia <strong>and</strong> Africa <strong>Group</strong> China Northwest Region: Dr. Shutian Li Nutrient Management <strong>and</strong> Balanced Fertilization in Ningxia Project Leader: Youhong Li, Soil <strong>and</strong> Fertilizer <strong>Institute</strong> (SFI), Ningxia Academy of Agricultural Sciences, Yinchuan, Ningxia. E-mail: youhongli@vip.sina.com, fangwang@vip.sina.com Project Cooperators: Fang Wang <strong>and</strong> Tiancheng Zhao Two experiments were conducted in 2011 in Ningxia province to: (a) investigate limiting nutrients for maximum rice yields by comparing the yields in optimal treatment (OPT) with yields obtained in nutrient omission plots; <strong>and</strong> (b) determine the optimal K rate for cabbage. An OPT trial in rice was conducted in Lingwu city. Results showed that the average yield with recommended OPT (225-90-75 kg N-P 2 O 5 -K 2 O/ha) was 10,292 kg/ha, which was 141%, 4%, <strong>and</strong> 2% more than that obtained plots omitting N, P, <strong>and</strong> K, respectively. This indicated N as the main limiting factor in rice production in Ningxia, while P <strong>and</strong> K were found to be sufficient. A potash rate trial in cabbage in Lingwu showed that increasing K rates increased cabbage yield by 13.1% to 20.8%. The highest cabbage yield was obtained with 300-150-225 kg N-P 2 O 5 -K 2 O/ha treatment. Increasing K rates to 300 kg K 2 O/ha reduced cabbage yield by 6.7%. However, there was no statistically significant yield difference between 225 <strong>and</strong> 150 kg K 2 O/ha treatments. Economic analysis showed that the highest income (USD 300/ha) was obtained in 150 kg K 2 O/ha treatment, which incidentally also had higher K recovery efficiency of all K treatments. In summary, the appropriate rate of K in cabbage in Lingwu, Ningxia, was found to be 150 kg K 2 O/ha. Ningxia-NMBF Nutrient Management <strong>and</strong> Balanced Fertilization in Inner Mongolia Project Leader: Debao Tuo, <strong>Institute</strong> of <strong>Plant</strong> <strong>Nutrition</strong> <strong>and</strong> Analysis (IPNA), Inner-Mongolia Academy of Agricultural Sciences (IMAAS), Huhhot, Inner Mongolia. E-mail: tuodb@263.net Project Cooperators: Yu Duan, Peiyi Zhao, <strong>and</strong> Huanchun Li Field trials were conducted on irrigated/rainfed potato, sunflower, <strong>and</strong> maize to demonstrate: (1) yield responses to balanced fertilization, <strong>and</strong> (2) effect of nutrient management under rain collecting or irrigation on crop yield <strong>and</strong> nutrient use efficiency. In flood irrigated potato in Wuchuan County, application of 240-90-165 kg N-P 2 O 5 -K 2 O/ha produced 44.3 t/ ha, which was 16%, 14%, <strong>and</strong> 12% more than the yields in N, P, <strong>and</strong> K omission plots, respectively. A rainfed potato trial produced 18.9 t/ha with 150-60-75 kg N-P 2 O 5 -K 2 O/ha, which was 22%, 30%, <strong>and</strong> 20% more than the yields in N, P, <strong>and</strong> K omission plots. Nitrogen <strong>and</strong> K recovery efficiencies under irrigation were 50% <strong>and</strong> 65%, while in rainfed conditions, these were lower at 22% <strong>and</strong> 39%, respectively. A study on rainfed potato at the Wuchuan Experimental Station found that plastic mulch coverage for collecting rainfall could produce 25% more tuber yield, <strong>and</strong> 9.9, 5.0, <strong>and</strong> 22% higher N, P, <strong>and</strong> K recovery efficiencies, respectively, as compared to no plastic mulch coverage. Sunflower experiments in Wuyuan County demonstrated highest seed yields under the optimum (OPT) treatment of 225-75-135 kg N-P 2 O 5 -K 2 O/ha. Agronomic efficiencies were 2.7 kg seed/kg N, 5.5 kg seed/kg P 2 O 5 , <strong>and</strong> 2.0 kg seed/kg K 2 O, <strong>and</strong> the average recovery efficiencies for N, P, <strong>and</strong> K fertilizer were 26.7, 17, <strong>and</strong> 54%, respectively. Compared with farmer practice (225-225-0 N-P 2 O 5 -K 2 O/ha), OPT produced 12.7% more seed yield <strong>and</strong> USD 494 more profit. Results from a sprinkler-irrigated maize trial at Dalate County, Erdos, revealed that application of 270- 120-180 kg N-P 2 O 5 -K 2 O/ha produced 39, 36, <strong>and</strong> 54% more grain yields than the N, P, <strong>and</strong> K omission plots. Application rates of N, P 2 O 5 <strong>and</strong> K 2 O for optimum economic yield were 238, 114, <strong>and</strong> 128 kg/ha, respectively. Accumulation of biomass <strong>and</strong> nutrient uptake in plastic mulch covered potato, sunflower, <strong>and</strong> sprinkler irrigated maize were also evaluated for future consideration regarding nutrient management in these crops. Inner Mongolia-NMBF IPNI Interpretive Summaries 79