|
Conservation agriculture originated in the US, and it was gradually promoted in ourcountry in1970s. At present, its main measures included zero tillage, subsoiling, rotary tillageand harrow tillage. Straw are important resource in agricultural circulation. Typicalproduction system of Huang-Huai-Hai regions, wheat-maize one year two ripe, as the mainresearch object in this experiment, the effect of straw returning and tillage methods on soilphysical and chemical properties and productivity was analysed. And soil quality evaluationsystem suitable for the land was established. Coupled with analysis the nutrients of differentcutting straw, a reference for choosing optimization system of straw returning and tillagemethods and using straw in this region could be provided. The main results were as follows.1Effects of straw returning and tillage methods on yield and component factorsCompared with conventional tillage, zero tillage reduced the grain number per ear ofmaize, number of productive ear and1000-grain weight of wheat, while subsoiling increasedthe yield of maize and zero tillage decreased the yield of wheat. From analyzing straw stubblereturning, straw returning could increase the1000-grain weight and grain number per ear ofmaize,1000-grain weight and number of productive ear of wheat, whlie increased with theamount of straw returning. The effect of stubble1m returning on maize and wheat yield wasthe best.2Effects of straw returning and tillage methods on soil physicochemical propertiesCompared with conventional tillage, conservation agriculture had significant effects onthe soil chemical properties, and zero tillage and subsoiling significantly increased organiccarbon, total nitrogen, total phosphorus, total potassium, available phosphorus, availablepotassium in0~20cm soil layer. Each index and conventional agriculture was distributeduniformly in0~40cm soil layer. Straw returning could significantly increased organic carbon,total nitrogen, total phosphorus, total potassium, available phosphorus, available potassium insoil, and increased larger of stubble1m returning, but all straw returning increased thegrowth lower.The effect of straw returning and tillage methods on soil physical properties and enzyme activity was significant. Compared with conventional agriculture, the soil bulk density andenzyme activity in zero tillage, subsoiling increased. Straw returning decreased soil bulkdensity and pH value, increased non-capillary porosity and water content in soil, in whichstubble1m returning increased considerably.3The farm soil quality evaluation under different straw returning to the field and tillagemethodsThe farm soil quality index was different under different straw returning to the field andtillage methods. The results showed that soil quality index was significantly correlated withyields. So soil quality index could reflect the quality and productivity level of soil. The Z-1treatment was the highest in soil quality index, and the PZ, S-1, C-1and PC treatments werehigher. But the AZ and AStreatments were lower. So the farm soil productivity was higherunder Z-1, PZ, S-1, C-1and PC, but it was lower under AZ and AS.4Nutrition in different harvest positions and yield analysis of maize stoverDifference of straw yield was significant annually, but the proportion of production ofdifferent harvest positions in total yield had no significant difference among years, dry weightand fresh weight yield above1m parts is less than1/3of total yield. From the analysis ofnutrition and sensory, above1m parts stayed green, the content of neutral and acid detergentfiber was the lowest, and the content of crude protein, crude fat, calcium and phosphorus wasthe highest, while potassium, sugar and water content is suitable. So above1m position is themost suitable for feeding.In order to improve farm soil physicochemical properties, increase yields and makerational use of maize straw, the subsoiling tillage should be chosen, the maize straw stubble1m should be returned directly and above1m parts is baled out farmland and used for feeding.
|