Methodology Of Fertilizer Recommendation Based On Yield Response And Agronomic Efficiency For Potato

Potato?Solanum tuberosum L.?is an important food crop in China,but China's prevailing level of potato yield has a big gap with developing country.Surveys in potato main production regions showed that unbalanced N,P and K fertilization,especially N over-fertilization is widespread among farmers'practice,and it is urgent to establish a fertilizer recommendation method for potato.The datasets used in this study were collected from multiple-year-site experiments.The Quantitative Evaluation of the Fertility of Tropical Soil?QUEFTS?model was used to simulate the optimal nitrogen?N?,phosphorus?P?and potassium?K?requirements of tuber and whole plant under different target yields.The relationship between yield response and agronomic efficiency of potato was analyzed to establish the recommendation method based on yield response and agronomic efficiency,and the user-friendly NE?Nutrient Expert?decision support system was established using information technology.Field validation experiments were implemented to update the related parameters used in NE system and evaluate agronomic,economic and yield effects of NE system.The main results obtained were shown below:?1?The average yield?fresh weight?of potato in China was 25.3 t/hm²,and the average harvest index was 0.73 kg/kg.The average contents of N,P and K in potato tuber were 15.4 g N/kg,2.8 g P/kg and 17.2g K/kg,respectively.And the average N,P and K contents of straw were 20 g N/kg,2.8 g P/kg and 14.2 g K/kg,respectively.The maximum dilution and maximum accumulation boundary parameters of N,P and K for QUEFTS were calculated by the upper and lower 2.5 percentiles of nutrient internal effiicnecies.The target yield and nutrient uptake was linearly distributed until target yield reached about 60%⁷0%of potential yield.To produce1000 kg potato tuber,3.9 kg N,0.7 kg P?2.9 kg K was required by the whole plant.The QUEFTS model simulated that tuber N,P and K uptake accounted for 76.7%,71.3%and 78.5%of the whole plant with the linear part at the potential yield of 30 t/hm².The potato dry matter and nutrients were mainly accumulated in tubers.?2?The average attainable yield with optimal treatments was 29.4 t/hm²,and the average yield responses to N,P₂O₅ and K₂O application were 8.6,5.9 and 6.6 t/hm² respectively,showing N was the first limited nutrient for potato yield in China.Among different regions,the average attainable yield and yield respinse of N ranked first in NE region?P<0.05?.The N,P or K rates averaged by 164.2kg N/hm²,100.3 kg P₂O₅/hm²,and 188.0 kg K₂O/hm² across different regions,and the average N and K rates in SE region were shown to be the highest values?P<0.05?.The average relative yields of N,P and K were 71.0%,79.4%and 77.2%,respectively,the average relative yields of N in NC,that of P in SE,that of K in NW were the highest across different regions.The average agronomic efficiency?AEs?of N,P and K were52.5 kg/kg N,58.5 kg/kg P₂O₅ and 42.3 kg/kg K₂O respectively,and AEs of N or K in NE was the significant?P<0.05?highest.The averaged partial factor productivity?PFPs?of N,P and K were 205.7 kg/kg N,339.0 kg/kg P₂O₅ and 209.2 kg/kg K₂O respectively,and those of N and K in NE was the significant?P<0.05?highest.The recovery efficiency?REs?of N,P and K averaged by 36.4%,18.2%and 27.4%respectively,and REs of P₂O₅ in SE were observed to be with the highest values?P<0.05?.?3?There was a significant?P<0.05?negative linear correlation between yield response and relative yield,and significant quadratic equation between yield response and agriculture efficiency of N,P and K for potato,respectively.On the basis,the fertilizer recommendation method based on yield response and agronomic efficiency was established and NE system was developed.?4?The field validation showed that NE treatment reduced N and P fertilizer rates by 73.4kg N/hm² and 57 kg P₂O₅/hm²,and increased K by 12.4 kg K₂O/hm² on average as compared with FP treatment.The NE treatment increased tuber yield by 3.2 t/hm²,and increased profitability by 4142.7 yuan/hm² on average compared with FP.NE treatments improved agronomic efficiency of N,P and K by 14.2 kg/kg N,15.9 kg/kg P₂O₅ and 9.4 kg/kg K₂O,partial factor efficiency by 45.2 kg/kg N,101.5 kg/kg P₂O₅ and 4.9 kg/kg K₂O,and increased recovery efficiency of N and P by 7.0 and 5.4 percentage points compared with FP respectively,but the recovery efficiency of K₂O declined due to increased K fertilizer input in most cases.In conclusion,the methodology of fertilizer recommendation based on yield response and agronomic efficiency for potato with scientific nutrient management principles could have higher yield,economic benefit and fertilizer use efficiency than FP in practice,which indicated that it was suitable for potato nutrient management in China.