| The shortage of water resources in the inland arid grassland area,the low yield of natural grassland pastures and the increasing degradation of grassland vegetation communities have severely restricted the cyclic development of the local animal husbandry and ecological environment.An important way to ensure the sustainable and healthy development of the soil environment.This study was carried out in Huajian Township Experimental Base,Suzhou District,Jiuquan City,with a typical arid climate from 2018 to 2019.The experiment adopts a complete block design,setting 7 irrigation modes and 2 planting methods.The experiment has a total of 14treatments,and each treatment has 3 repeats.By exploring the effects of different irrigation patterns and planting methods on dry matter yield,quality and water use of artificial grasslands,the aim is to obtain a management model suitable for high-yield,high-quality and water-saving grasslands in the inland arid grasslands of northwestern China.The following conclusions are obtained:?1?Under different irrigation modes,the grassland soil water content increases with the increase of the irrigation water limit.In the two growing seasons,the average water content of the CK treatment is higher than that of other irrigation treatments,the A4 treatment has the lowest irrigation water content,and the lowest soil water content.During the planting period and the greening period,there was no obvious regularity of soil moisture between different treatments,but they all showed a higher depth of soil moisture.The soil moisture content of treatments at jointing stage differed significantly in each treatment.The soil water content in the treatment with high irrigation limit was significantly higher than that in the treatment with low irrigation limit,and the soil water content in the heading stage A1,A2 and A3treatment was significantly higher than that in the jointing stage.Under the same treatment,the water content gradually increased with the depth of the soil layer.Affected by irrigation and rainfall,the soil water content of the 0-60 cm soil layer fluctuated greatly in each treatment,while the change of the deep soil water content was small.As the growth period of pastures advances,the moisture content of the deep soil of each treatment gradually decreases.Compared with alfalfa,the awnless brome has a shallower root system,so the mixed soil is more obvious than the monoculture grassland.The soil moisture content decreases with the growth period.?2?In the 2019 growing season,under the same irrigation pattern,the dry matter yield of forage grass gradually decreases with the number of stubble cuts.The dry matter yield of forage grass increased with the increase of irrigation volume,of which the dry matter yield of CK irrigation mode was the highest.The yields of the first stubble and mixed sowing in 2019 were 3844.02 kg hm-22 and 8644.48 kg hm-2,respectively;under A4 irrigation mode The dry matter output is the lowest,and the third crop in 2019 is only 1288.25 kg hm-2?unicast?and 2696.77 kg hm-2?mixed?.Forage irrigation volume increased gradually with the increase of irrigation water limit,and water consumption increased with irrigation volume.The irrigation volume of CK treatment was significantly higher than that of other treatments.Among them,the irrigation volume of unicast and mixed broadcast in CK irrigation mode in 2018was 277.91 mm and 318.56 mm,respectively.The irrigation volume of stubble unicast and mixed sowing were 40.23 mm and 60.54 mm,respectively.Forage grass rehydration after the water deficit at the jointing stage can significantly increase the yield of forage grass.The sensitivity and demand of forage to water in heading stage is higher than that in jointing stage.In the two growing seasons,the A1,A2,and A3treatments increased the irrigation limit at the heading stage,and the yield increased significantly compared to the A4,A5,and A6 treatments.Appropriate irrigation patterns and planting methods can significantly improve the efficiency of forage water use.Among the 7 irrigation modes,the dry matter water use efficiency of A4treatment reached the highest?2.07 kg hm-33 and 3.18 kg hm-33 for unicast and mixed broadcast,respectively?,and the dry matter water use efficiency of CK treatment was the lowest,only 0.89 kg hm-3?unicast?and 1.69 kg hm-3?mixed broadcast?.Compared with unicast,the water use efficiency of each treatment under mixed broadcast conditions can be significantly improved by 36.36%-95.56%.The A3 treatment can save irrigation and improve the water use efficiency of forages without significantly reducing yield.It can be seen that the combination of mixed planting and irrigation at the jointing stage irrigation limit of 65%FC and heading stage irrigation limit of75%FC can achieve higher forage yield and water use efficiency.Under different irrigation modes,the crude protein content of the forage increased with the decrease of the irrigation amount,and the lowest crude protein content of the forage under CK treatment,of which the lowest value of crude protein content of the awnless brome was 9.58%and 10.46%under unicast and mixed seeding conditions,respectively.The minimum value of crude protein content of alfalfa is 17.26%.The crude protein content of the forage reached the maximum under the A4 irrigation mode,and the highest protein content of the awnless brome under the third A4 treatment in 2019 was 14.97%for unicast and 15.48%for mixed seeding.Under the same irrigation pattern,the crude protein content of the mixed grass awnless brome increased by 2.97%-3.63%compared with the unicast grass.The content of forage fiber decreased first and then increased with the increase of irrigation volume.Under CK and A4 irrigation modes,the acidic cleaning fiber content of awnless brome and alfalfa was significantly higher than other treatments.Under the A3 irrigation mode,the acidic washing fiber content of the awnless brome and alfalfa was the smallest.The minimum value of the acidic washing fiber of the awnless brome in unicast and mixed sowing was 25.31%and 23.62%,respectively,and the minimum value of alfalfa was 22.51%.The change rule of the content of neutral detergent fiber between treatments was basically the same as that of acid detergent fiber.It decreased first and then increased with the increase of irrigation volume.The content of neutral detergent fiber in CK and A4 irrigation modes was significantly higher than that of other treatments.In the A3 irrigation mode,the acidic washing fiber content of awnless brome and alfalfa was the smallest.The minimum value of neutral washing fiber content of awnless brome in single and mixed sowing was 35.44%and 34.67%,respectively,and the content of alfalfa was 31.26%.Appropriate water stress can increase the yield of forage crude protein while saving water,but excessive water stress will significantly reduce the yield of forage crude protein.Among them,there is no significant difference in the crude protein yield of A3 and CK treatment.The crude protein of forage under A4 irrigation mode The output is significantly lower than other treatments.Water regulation can significantly improve the water use efficiency of forage crude protein.The water use efficiency of forage crude protein reached the maximum under the A4 irrigation mode,which was0.26 kg hm-33 and 0.66 kg hm-33 under unicast and mixed seeding conditions,respectively.Compared,the water use efficiency of mixed grassland crude protein can be increased by 100.00%-219.29%.It can be seen that the irrigation mode of mixed planting combined with 65%FC at jointing stage and 75%FC at heading stage can obtain better forage quality. |
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