Effects Of Soil Nutrient Content On Potato Tuber Yield And Quality In North Shaanxi Province

Potato is suitable for planting in Northern Shaanxi Province.It is one of the five dominant potato growing areas in China.Because of the lacked of quantitative description of potato field yield and quality,the main factors of soil nutrient factors that limit the increase in potato yield were not clearly defined,and the relationship between potato quality and soil nutrients was unclear.Therefore,it affects the formulation of agricultural measures to increase potato production,which seriously affects the market competitiveness and economic benefits of potatoes.This study conducted potato field investigation experiments in North Shaanxi Province from 2017 to 2018.The potato tuber quality and soil nutrient content were used as research materials in the region,combined with indoor agrochemical experiments,obtained basic research data on potato yield,potato quality characteristics,and soil nutrient status.This experiment was carried out to study the potato of yield potential and yield gap,and the relationships between potato yield and soil nutrient factors,which were analyzed using the grey correlation method in North Shaanxi Province.The object of this experiment was to explore the relationships between soil nutrients and potato quality indexes were determined by Partial Least Square Regression(PLSR).And screen out the main soil nutrient factors,which affecting quality characteristics.The paper established the Minimum Data Sets(MDS)for quality diagnosis of cultivated layer for farmland by principal component analysis respectively.Soil Quality Index(SQI)was used to analyze the soil quality characteristics of cultivated land.In this paper,the soil fertility and the vertical distribution of soil nutrients in North Shaanxi Province were studied.The main results are as follows:1)The classification of potato tuber yield and tuber yield gap in Loess Plateau are as follows,the high-yield group at the potato experimental station(HE)was 72,678 kg/hm~2;the mean-yield group at the potato experimental station(ME)was 36,083 kg/hm~2;the high-yield group in the potato planting farmland(HF)was 34,259 kg/hm~2;And the mean-yield group in the potato planting farmland(MF)was 19,386 kg/hm~2.The yield gap(YG1)between HF and MF was 14,873 kg/hm~2;The yield gap(YG2)between ME and the MF was 16,697 kg/hm~2;The yield gap(YG3)between HE and the MF was53,291 kg/hm~2.2)The effects of soil moisture and nutrients on potato yield were ranked from large to small:soil available potassium content>soil nitrate nitrogen content>soil organic matter content>soil water content>soil available phosphorus content.The results of correlation analysis and grey correlation analysis showed that the available potassium had the strongest correlation with potato tuber yield.3)The results showed that the major soil nutrient factors influencing the potato tuber quality in North Shaanxi Province were soil ammonium nitrogen,soil nitrate nitrogen,soil available phosphorus,pH,and soil available potassium.Soil pH value was the most important factor affecting potato starch,reducing sugar content,and soluble protein content.Soil nitrate nitrogen is one of the important factors affecting potato tuber soluble total sugar content,vitamin C,browning intensity,and polyphenol oxidase activity.The results showed that the major soil nutrient factors influencing potato tuber quality were soil nitrate nitrogen and soil pH value.4)Soil available nitrogen had positive correlations with soluble total sugar in potato quality,negative correlated with browning intensity in potato quality;Nitrate nitrogen had positive correlations with reducing sugar,vitamin C,browning intensity and polyphenol oxidase in potato quality,negative correlated with soluble total sugar in potato quality;Ammonium nitrogen had positive correlations with soluble total sugar in potato quality,negative correlated with reducing sugar,browning intensity and polyphenol oxidase in potato quality.Soil Available phosphorus had positive correlations with soluble total sugar and coarse protein in potato quality,negative correlated with reducing sugar,vitamin C and browning intensity in potato quality.Soil Available potassium had positive correlations with starch and reducing sugar in potato quality,but negatively correlated with coarse protein and browning intensity in potato quality.5)The MDS on soil quality diagnosis of cultivated layer for soil farmland included such indicators as Soil organic matter content,Soil available potassium content and Soil available phosphorus content.The proportion of soil nutrients in SQI composition ranged from large to small as Soil available potassium content?Soil available phosphorus content>Soil organic matter content,which became the limiting factor of Soil organic matter content in this area.6)The comprehensive index value of the soil quality was between 0.064 and 0.302,SPSS average clustering process was used to classify SQI was divided into three grades,the class I(36.2%)was defined suitable soil fertility(SQI<0.122),the class II(55.6%)was defined moderate soil fertility(0.122<SQI<0.18),and the class III(8.2%)was defined poor soil fertility(SQI>0.186),the comprehensive quality of the potato farmland soils was generally low.7)In this study,the vertical 0-60 cm soil was divided into three layers.The average SQI of S1 soil layer(0-20 cm)was 0.160,the average SQI of S2 soil layer(20-40 cm)was 0.113,and the average value of SQI of S3 soil layer(40-60 cm)was 0.101,and the SQI value of each soil layer is significantly different.Among them,the class III of SQI in soil layer S1 accounts for 22.2%,the class II accounts for 17.3%,and the class I accounts for 60.5%;the class III of SQI in soil layer S2 accounts for 2.5%,the class II accounts for71.6%,and the class I accounts for 25.9%;the class III of SQI in soil layer S3 accounts for 0,the class II accounts for 77.8%,and the class I accounts for 22.2%.The results showed that the potato yield per unit area is low in Northern Shaanxi Province,the factors of soil nutrient have a greater influence on potato yield and quality,the soil nutrient content in the region is relative low and precipitation is insufficient.It is suggested to improve the soil nutrient status in this region,the input of organic fertilizer and nitrogen fertilizer need to be increased,and reasonable application of potassium fertilizer,and integrated water and fertilizer cultivation measures be implemented,so as to improve the potato yield and quality characteristics.