| Organic substrates culture in greenhouses—a highly efficient biological cultivation pattern, havebeen promoted widely in the Gobi Desert Regions of Northwest China due to their advantages in fullyusing the large areas of non-arable lands and the rich light and heat resources in that areas. Theextension of the substrate cultivation play important role in ensuring vegetable perennial supply andimproving local farmer’s living standards, and the abundant wastes are recycled as the cultivationsubstrates are mainly composed of organic by-products. Fertilizer application is one of the indispensabletechnologies for the high-yield and good-quality vegetable production in the greenhouse-substratesculture. Many studies have reported fertilization techniques of vegetable cultivated in greenhouseorganic substrates, but there is still not enough information about the sustainable supply of nutrientscoordinated with the demand of the whole growth period of vegetables in the non-arable land ofNorthwest China. In this research, the methods of field survey, field plot experiments and laboratorialanalysis were combined used to study the physical and chemical properties of organic cultivationsubstrates, the fertilization status in greenhouse vegetable fields in Gobi desert regions, Gansu Province,the variations of NPK nutrient supplies of the present fertilization way in greenhouse substratecultivation and the demands of cucumber and tomato cultivated. The effect of balanced NPK fertilizermanagement on the yields and nutrient uptakes were tested in cucumber and tomato. The results willprovide scientific fertilization bases in the rapid development of efficient greenhouse-substratescultivation patterns of vegetables in the non-arable land of Northwest China. The main results obtainedare summarized as follows:1. Physical and chemical properties of organic cultivation substrates and vegetablefertilization status in greenhouse vegetable fields in Gobi desert regionsThis study was conducted to determine status of available nutrients and total nutrients ofrepresentative organic cultivation substrates samples, and vegetable fertilization status in greenhousevegetable fields in Gobi desert regions, Gansu Province. The results showed that:(1) Contents ofNO3--N in most cultivation substrate samples were at high evaluation levels in Linze experimentalregion, but at medium and low evaluation levels in Suzhou experimental region. Contents of available Pand K in cultivation substrates in Linze and Suzhou experimental regions were generally at highevaluation levels. In Linze and Suzhou experimental regions, available S, Fe, Zn and B contents were athigh evaluation levels, Cu at relatively high evaluation levels, and Mn at above medium evaluationlevels. Cultivation substrates in Linze and Suzhou experimental regions were abundant in the amount oftotal N, P and K, seriously deficient or deficient in the amount of available N, extremely adequate in theamount of available P, and moderately adequate in the amount of available K. Vegetable nitrogen andpotassium requirements are much higher than that of phosphorus. Nutrient management of vegetablecultivated in greenhouse organic substrates should focus on N and K, to less extent on P to maintainrelatively high supply capacity of N and K in cultivation substrates.(2) Excessive fertilization were verycommon in the two monitored areas, especially in P application. In Linze, the average application rates of N, P2O5and K2O were2.2,10.5and5.3times of their practical requirements, in Suzhou, those were1.6,3.7and3.2times in cucumber production, and the average application rate of P2O5for tomato were3.7times of its practical requirements. The proportion of nutrients supplied by organic manure weredistinctly low in tomato of the winter-spring season in Suzhou and autumn-winter season in Linze; Theratios of basal fertilizer were too high in spring season cucumber and autumn-winter season tomato inSuzhou.2. Changes of nutrient supply and demand during the growth period of cucumber andtomato cultivated in greenhouse organic substrates in Gobi desert regionsThis study was conducted to determine changes in amount of available nitrogen, phosphorus andpotassium in organic cultivation substrates and accumulation rates of nitrogen, phosphorus andpotassium in the whole plant (plant+fruit) during growth period of autumn-winter tomato, springtomato and spring cucumber cultivated in greenhouse organic substrates in Gobi desert regions. Theresults showed that:(1) During the growth period of autumn-winter tomato, spring tomato and springcucumber, amount of available N in cultivation substrates were generally in medium and low evaluationlevels, and tended to decrease slowly until a relatively contstant value; amount of available P2O5incultivation substrates were generally in high evaluation levels, and tended to decrease slowly until arelatively contstant value; amount of available K2O in cultivation substrates displayed a tendency todecrease fastly from a high value (before transplanting) until a relatively constant value, with theamount sharply decreasing by34.5%-52.1%at fruit growth stage.(2) Accumulation rates tended toincrease slowly until a relatively constant value for N and P2O5in the whole plant of autumn-wintertomato, spring tomato and spring cucumber, and increase fastly until a relatively constant value for K2Oin the whole plant. The peak accumulation rates of N, P2O5and K2O in the whole plant appeared at fruitgrowth stage, with the accumulation rates of N, P2O5and K2O respectively being74.1%-89.2%,81.0%-86.8%and82.1%-92.7%of corresponding total accumulation rates during growth period ofautumn-winter tomato, spring tomato and spring cucumber.3. Balanced fertilization techniques of nitrogen, phosphorus and potassium of cucumber andtomato cultivated in greenhouse organic substrates in Gobi desert regionsThe effects of balanced fertilization of nitrogen, phosphorus and potassium on yields and nutrientuptake of spring cucumber and autumn-winter tomato cultivated in greenhouse organic substrates werestudied. The results showed that:(1) Nitrogen and potassium were the major nutrient limited factors forspring cucumber and autumn-winter tomato cultivated in greenhouse organic substrates. Phosphorusapplication had also certain effect to increase yield. Nitrogen, potassium and phosphorus applicationrespectively increased spring cucumber yield by51.2%,45.2%and10.0%, and increasedautumn-winter tomato yield by31.2%,17.0%and4.1%.(2) Compared with the conventionalfertilization, balanced fertilization of nitrogen, phosphorus and potassium significantly respectivelyincreased the yields of spring cucumber and autumn-winter tomato by35.7%and16.3%, and increasedthe economic income by40.7%and17.5%. Compared with the high N treatment and the high Ktreatment, balanced fertilization treatment slightly respectively increased yield and economic income by 3.0%-4.8%and3.2%-4.9%.(3) Balanced fertilization of nitrogen, phosphorus and potassium distinctlyimproved or maintained nutrient uptake of spring cucumber and autumn-winter tomato, andsignificantly increased the recovery rate of nitrogen, phosphorus and potassium chemical fertilizer by25.8%-31.7%,17.6%-34.1%and35.7%-78.9%, respectively. Whereas the recovery rate of nitrogen,phosphorus and potassium chemical fertilizer by conventional fertilization were only4.6%-15.9%,0.9%-6.5%and11.7%-19.7%, respectively.(4) Under the field experimental conditions, proper N, P2O5and K2O application rates of spring cucumber in greenhouse substrates culture were respectively400,150and400g/m3substrates, and N, P2O5and K2O recommendation rates for1000kg production ofspring cucumber were respectively2.2,0.8and2.2kg. Proper N, P2O5and K2O application rates ofautumn-winter tomato in greenhouse substrates culture were respectively392,136and455g/m3substrates, and N, P2O5and K2O recommendation rates for1000kg production of autumn-winter tomatowere respectively3.1,1.1and3.6kg. |
PDF Full Text Request