Influence of crop straw residue return on crop yield and soil nutrient status

Transcription

1 Influence of crop straw residue return on crop yield and soil nutrient status Shihua Tu Southwest China Program Soil and Fertilizer Institute, SAAS Better Crops, Better Environment through Science

2 Outline Background Crop residue decomposition and nutrient release Crop responses to different fertilizer treatments under/no straw mulch with no-till Effect of crop residue return on soil nutrient status Conclusions

3 Background In 2000 s, farmers started straw burning in field in Sichuan province Straw burning caused air pollution, loss of C (90-97%), N (98-100%), S (70-90%), P and K (20-40%) to air. Severe smoke forced close of Chengdu Airport for a few times.

4 Background Why did farmers burn crop residues in field? Traditional use of crop residues: Cattle feed Cooking Paper making Thatching 10 years ago: Rural labors migrating into cities No-till and machine replaced labor oxen Natural gas/coal replaced cooking wood Modern houses no longer use crop straw Paper mills no longer use straw. Under this situation, research projects were initiated to solve the problem. The objectives of our project were to study how to better use crop residues as nutrient sources and to find out the best nutrient management when crop straw is returned to soil.

5 Rate and Time of Crop Residue Decomposition and Nutrient Release

6 Growing area and Straw yield of rice, wheat, corn and rapeseed in Sichuan in 2010 Rape Rice Corn Rape Rice Corn Wheat Wheat Grown area in thousand ha Straw yield in million t The estimated annual production of straw for the four crops is about 30 million t.

7 Crop Residues - Valuable Plant Nutrient Sources Residue Nutrient content (%) Nutrient content (kg/ha) N P K N P K Rice Wheat Rape Total nutrient content: rice straw > wheat straw > rape stalk; K>N>P 0.826

8 Decomposition rates of wheat and rapeseed residues in paddy rice season Crop residue Sampling date June 5 June 25 July 15 Aug 4 Aug 24 Sept 4 Days (since May 26) Dry matter lost(g) Wheat Accumulative loss (%) Average loss (g/d) Dry matter lost(g) Rapeseed Accumulative loss (%) Average loss (g/d) Dry weight loss was the fastest at the first 30 d for wheat straw (41%) and the first 10d for rapeseed stalk (24.5%)

9 Accumulated Nutrient release (%) Accumulated nutrient release (%) N, P and K release from wheat straw and rapeseed stalk with time in the paddy field N P K N P K Decomposition time(d) Decomposition time (d) Wheat straw Rape stalk The fastest nutrient release in the first 10 d, K in particular (>97%);followed by P (73% for wheat straw,63% for rape stalk);and then N (34% for wheat straw, 36% for rape stalk). At rice harvest, 99% of N, 81% of P and 74% of K released from wheat straw;99% of N, 78% of P and 69% of K released from rape stalk.

10 Accumulated Nutrient release(%) K released within 1st 10 d when straw soaked in water Wheat Rape Decomposition time(d) Soaked in water for 2d, K was released up to 71% from wheat straw,69% from rape straw;up to 95% in 10 d for both straws, indicating K in straw highly soluble and readily available.

11 Decomposition Process of wheat straw under waterlogged conditions

12 Decomposition of tissue structure of wheat straw in field(x20) 10d 30d 50d 70d 90d 100d After wheat straw was returned to field, its tissue structure decomposed slowly at very beginning. At 30d,only parenchyma cells started to decompose; at 70d, severe destruction of parenchyma cells, bundle sheath and some broken air cavity were observed; at100d, severer destruction of these tissues proceeded.

13 Decomposition Process of rape stalk under waterlogged conditions

14 Decomposition of tissue structure of rape stalk in field (x4) 10d 30d 50d 70d 90d 100d For rape stalk, decomposition mainly took place in the first 10 d: the vascular cambium, phloem fibres, parenchyma and epidermis above the metaxylem were damaged; the stake pith empted. The metaxylem became thinner and thinner thereafter.

15 Decomposition rate of rice straw under surface mulch and buried in wheat field Treatment Sampling date Oct 7 Oct 27 Nov 26 Jan 6 March 26 April 25 Time (d) Dry matter loss(g) Surface mulch Accumulated loss (%) Average loss (g/d) Dry matter loss(g) Bury in soil Accumulated loss (%) Average loss (g/d) Whether surface mulched or buried,dry matter loss was the highest in the 1rst 10d, buried straw decomposed much faster than surface mulch. At wheat harvest, rice straw decomposed to 76.6%, 23% higher than surface mulch

16 Accumulated nutrient release (%) 养分累计释放率 (%) Accumulated nutrient release (%) 养分累计释放率 (%) Comparison in nutrients release from wheat straw between the surface mulch and the soil burial Surface mulch N P K Buried into soil N P K 腐解时间 (d) 腐解时间 (d) (1) 稻草覆盖 Release of K was fastest at 1st 10 d, 50% for surface mulched straw and 90% for the burial; similar for P and K. At end of the experiment, release of P and K from the buried straw reached 72% and 56%, and 42% and 23% from surface mulched straw.

17 Mineralization of soil N as affected different treatments

18 Crop Responses to Different Fertilizer Treatments under/no Straw Mulch with No-till

19 Experiment Design Rice wheat rotation Rice Wheat Rice rapeseed rotation Rice Rapeseed N 150 P 60 K 90 (CK) N 150 P 75 K 90 (CK) N 165 P 60 K 90 (CK) N 180 P 90 K 90 (CK) N 90 P 60 K 90 (W) N 90 P 75 K 90 (R) N 75 P 60 K 90 (RS) N 120 P 90 K 90 (R) N 120 P 60 K 90 (W) N 120 P 75 K 90 (R) N 105 P 60 K 90 (RS) N 150 P 90 K 90 (R) N 150 P 60 K 90 (W) N 150 P 75 K 90 (R) N 135 P 60 K 90 (RS) N 180 P 90 K 90 (R) N 180 P 60 K 90 (W) N 180 P 75 K 90 (R) N 165 P 60 K 90 (RS) N 210 P 90 K 90 (R) N 120 P 60 K 60 (W) N 150 P 75 K 45 (R) N 105 P 60 K 60 (RS) N 180 P 90 K 60 (R) N 120 P 60 K 0 (W) N 150 P 75 K 0 (R) N 105 P 60 K 0 (RS) N 180 P 90 K 0 (R) N 120 P 0 K 90 (W) N 150 P 0 K 90 (R) N 105 P 0 K 90 (RS) N 180 P 0 K 90 (R) Where the subscripts of N, P and K refer to rates (kg/ha) of N, P 2 O 5 and K 2 O applied, CK control (chemical fertilizer only), W soil mulched with wheat straw, R soil mulched with rice straw and RS soil mulched with Rapeseed straw. All the crop residue in a plot is returned back after harvest.

20 Rice yields as affected by different treatments under rice wheat rotation in Treatment rice yield (kg/ha) N 150 P 60 K 90 (CK) 9549 abc 9811 a 9655 c 9174 cd 8574 c 8078 cd N 90 P 60 K 90 (W) 9251 c a ab 9156 d 8504 c 7544 e N 120 P 60 K 90 (W) ab 9578 ab abc 9753 a 9000 ab 7950 d N 150 P 60 K 90 (W) 9810 abc a a 9693 ab 9148 a 8651 a N 180 P 60 K 90 (W) a 8847 c abc 9424 bc 8593 c 8486 ab N 120 P 60 K 60 (W) 9752 abc 9718 ab abc 9521 ab 9345 a 8265 bc N 120 P 60 K 0 (W) 9441 bc 9296 bc 9929 bc 9453 b 8568 c 7830 de N 120 P 0 K 90 (W) 9994 abc 9650 ab abc 9649 ab 8687 bc 8430 ab

21 Wheat yields as affected by different treatments under rice wheat rotation in Treatment Wheat yields in (kg/ha) N 150 P 75 K 90 (CK) 7500 d 4883 c 5497 d 6007 d 7950 c 5183 c N 90 P 75 K 90 (W) 7842 bcd 4995 abc 5815 c 6039 c 7621 d 5200 c N 120 P 75 K 90 (W) 7603 cd 5171 abc 6208 b 6290 b 8215 b 5389 c N 150 P 75 K 90 (W) 7962 bcd 5534 ab 6494 a 7041 a 8300 b 6193 b N 180 P 75 K 90 (W) 8207 ab 5576 a 6595 a 6781 a 8576 a 6503 a N 150 P 75 K 45 (W) 8006 bc 4843 c 6084 b 6427 b 8380 ab 6120 b N 150 P 75 K 0 (W) 7865 bcd 4927 bc 5757 c 5581 c 7869 cd 6030 b N 150 P 0 K 90 (W) 8494 a 4901 c 6141 b 6268 b 7680 d 6181 b

22 Straw mulch NP CK NPK

23 Fertilizers saved with crop straw return under rice wheat rotation Based on the CK treatments of kg N-P 2 O 5 - K 2 O/ha for rice and kg N-P 2 O 5 -K 2 O/ha for wheat. Straw return can save about 60 kg N, 135 kg P 2 O 5 and kg K 2 O /ha a year.

24 Rice yields as affected by different treatments under rice rapeseed rotation in Treatment rice yield (kg/ha) N 165 P 60 K 90 (CK) 9423 a 9776 a b c c c N 75 P 60 K 90 (C) 9173 a a ab bc a bc N 105 P 60 K 90 (C) 9546 a a a ab a bc N 135 P 60 K 90 (C) 9467 a a a a a a N 165 P 60 K 90 (C) 9175 a 9855 a ab a a a N 105 P 60 K 60 (C) 9332 a 9768 a a a b bc N 105 P 60 K 0 (C) 9260 a 9845 a a ab b ab N 105 P 0 K 90 (C) 8866 a a ab a b ab

25 Rapeseed yields as affected by different treatments under rice rapeseed rotation in Treatment Rapeseed yields in (kg/ha) N 180 P 90 K 90 (CK) 4077 cd 3770 bc 1895 a 3941 b 4087 c 4718 d N 120 P 90 K 90 (R) 4200 bc 3394 e 1800 a 3939 b 3915 d 4647 d N 150 P 90 K 90 (R) 4209 bc 3592 cd 1915 a 4018 b 4182 bc 4824 cd N 180 P 90 K 90 (R) 4367 ab 4371 a 1941 a 3969 b 4303 ab 5021 bc N 210 P 90 K 90 (R) 4303 ab 3937 b 1883 a 4215 ab 4405 a 5309 a N 180 P 90 K 60 (R) 4450 a 3752 bc 1865 a 4351 a 4394 a 5105 ab N 180 P 90 K 0 (R) 4231 abc 3869 b 1878 a 4186 ab 4192 bc 5114 ab N 180 P 0 K 90 (R) 3859 d 3555 de 1823 a 3093 c 3473 e 3707 e

26 Fertilizers saved with crop straw return under rice rape rotation Based on the CK treatments of kg N-P 2 O 5 - K 2 O/ha for rice and kg N-P 2 O 5 -K 2 O/ha for wheat. Straw return can save 60 kg N, >60 kg P 2 O 5 and ~180 kg K 2 O /ha a year.

27 Readily and slowly available K in different regions of Sichuan province 成都平原区 Chengdu Plane 川中丘陵区 Central hilly region 川西南山地区 Southwest mountains 川西北高原山地区 Northwest mountains 盆周山区 Peri-mountain region Readily 速效钾 avail (mg/kg) K (mg/kg) slowly 缓效钾 avail (mg/kg) K (mg/kg)

28 Effect of K fertilizer on increase of crop yield in Sichuan province Region Sichuan Province Chengdu Plane Central hilly area Peri-mountain area South mountains Treatment Yield increase Yield (kg/ha) increase(%) N 2 P 2 K N 2 P 2 K N 2 P 2 K N 2 P 2 K N 2 P 2 K N 2 P 2 K N 2 P 2 K N 2 P 2 K N 2 P 2 K N 2 P 2 K N 2 P 2 K N 2 P 2 K N 2 P 2 K N 2 P 2 K N 2 P 2 K Data source: Sichuan Department of Agriculture, 2012

29 Effect of Crop Residue Return on Soil Nutrient Status

30 Soil total N and available N in the rice wheat rotation as affected by different treatments Treatment Total N (g/kg) 0-5cm 5-15cm Initial value in N 150 P 75 K 90 (CK) 1.88 b 1.53 b N 90 P 75 K 90 (R) 2.16 a 1.70 a N 120 P 75 K 90 (R) 2.20 a 1.75 a N 150 P 75 K 90 (R) 2.25 a 1.77 a N 180 P 75 K 90 (R) 2.31 a 1.80 a N 150 P 75 K 45 (R) 2.18 a 1.75 a N 150 P 75 K 0 (R) 2.21 a 1.76 a N 150 P 0 K 90 (R) 2.17 a 1.74 a Treatment Available N 0-5cm 5-15cm Initial value in N 150 P 75 K 90 (CK) c a N 90 P 75 K 90 (R) bc a N 120 P 75 K 90 (R) ab a N 150 P 75 K 90 (R) ab a N 180 P 75 K 90 (R) a a N 150 P 75 K 45 (R) ab a N 150 P 75 K 0 (R) ab a N 150 P 0 K 90 (R) ab a All the soil nutrients are much higher at 0-5 cm layer than at 5-15 cm layer; and in the straw mulched treatments than the CK. (Tian et al., 2008; Sun et al., 2008; Wu et al., 2012)

31 Soil total P and available P in the rice wheat rotation as affected by different treatments Treatment Total P (g/kg) 0-5cm 5-15cm Initial value in N 150 P 75 K 90 (CK) 0.68 a 0.47 a N 90 P 75 K 90 (R) 0.85 a 0.56 a N 120 P 75 K 90 (R) 0.78 a 0.57 a N 150 P 75 K 90 (R) 0.75 a 0.57 a N 180 P 75 K 90 (R) 0.70 a 0.57 a N 150 P 75 K 45 (R) 0.88 a 0.62 a N 150 P 75 K 0 (R) 0.95 a 0.62 a N 150 P 0 K 90 (R) 0.71 a 0.53 a Treatment Available P 0-5cm 5-15cm Initial value in N 150 P 75 K 90 (CK) 27.6 cd 7.4 bc N 90 P 75 K 90 (R) 38.0 a 9.8 ab N 120 P 75 K 90 (R) 37.5 a 9.7 ab N 150 P 75 K 90 (R) 30.2 b 7.5 bc N 180 P 75 K 90 (R) 34.7 ab 8.0 bc N 150 P 75 K 45 (R) 31.6 abc 8.4 bc N 150 P 75 K 0 (R) 34.6 ab 9.1 abc N 150 P 0 K 90 (R) 25.6 cd 6.9 c Soil available P Olsen P

32 Soil total K and available K in the rice wheat rotation as affected by different treatments Treatment Total K (g/kg) 0-5cm 5-15cm Treatment 0-5cm Available K 5-15cm Initial value in N 150 P 75 K 90 (CK) 18.8 a 18.6 a N 90 P 75 K 90 (R) 21.1 a 20.7 a N 120 P 75 K 90 (R) 23.1 a 19.7 a N 150 P 75 K 90 (R) 23.2 a 22.8 a N 180 P 75 K 90 (R) 25.0 a 22.1 a N 150 P 75 K 45 (R) 22.8 a 19.8 a N 150 P 75 K 0 (R) 22.8 a 19.8 a N 150 P 0 K 90 (R) 24.3 a 20.4 a Initial value in N 150 P 75 K 90 (CK) b b N 90 P 75 K 90 (R) a ab N 120 P 75 K 90 (R) a ab N 150 P 75 K 90 (R) a a N 180 P 75 K 90 (R) ab ab N 150 P 75 K 45 (R) b a N 150 P 75 K 0 (R) b ab N 150 P 0 K 90 (R) a ab Available K - sodium tetraphenyl-boron method Straw much increased soil K and the K had lower soil available K (Zhang et al., 2012)

33 Soil total N and available N in the rice rape rotation as affected by different treatments Treatment Total N (g/kg) 0-5cm 5-15cm Initial value in N 180 P 90 K 90 (CK) 1.92 b 1.55 b N 120 P 90 K 90 (R) 2.10 a 1.70 a N 150 P 90 K 90 (R) 2.13 a 1.72 a N 180 P 90 K 90 (R) 2.11 a 1.71 a N 210 P 90 K 90 (R) 2.50 a 2.03 a N 180 P 90 K 60 (R) 2.21 a 1.79 a N 180 P 90 K 0 (R) 2.36 a 1.91 a N 180 P 0 K 90 (R) 2.10 a 1.70 a Treatment Available N (mg/kg) 0-5cm 5-15cm Initial value in N 180 P 90 K 90 (CK) c c N 120 P 90 K 90 (R) c c N 150 P 90 K 90 (R) abc abc N 180 P 90 K 90 (R) ab ab N 210 P 90 K 90 (R) ab a N 180 P 90 K 60 (R) bc abc N 180 P 90 K 0 (R) abc abc N 180 P 0 K 90 (R) a abc

34 Soil total P and available P in the rice rape rotation as affected by different treatments Total P (g/kg) Treatment 0-5cm 5-15cm Initial value in N 180 P 90 K 90 (CK) 0.43 a 0.33 a N 120 P 90 K 90 (R) 0.52 a 0.39 a N 150 P 90 K 90 (R) 0.50 a 0.31 a N 180 P 90 K 90 (R) 0.46 a 0.31 a N 210 P 90 K 90 (R) 0.44 a 0.27 a N 180 P 90 K 60 (R) 0.42 a 0.34 a N 180 P 90 K 0 (R) 0.44 a 0.36 a N 180 P 0 K 90 (R) 0.44 a 0.30 a Treatment Available P (mg/kg) 0-5cm 5-15cm Initial value in N 180 P 90 K 90 (CK) 11.7 ab 6.5 ab N 120 P 90 K 90 (R) 16.8 a 7.0 a N 150 P 90 K 90 (R) 11.7 ab 5.8 ab N 180 P 90 K 90 (R) 13.3 ab 6.3 ab N 210 P 90 K 90 (R) 13.7 ab 6.9 a N 180 P 90 K 60 (R) 11.8 ab 7.8 a N 180 P 90 K 0 (R) 12.0 ab 6.1 ab N 180 P 0 K 90 (R) 9.8 b 4.5 b Soil available P Olsen P

35 Soil total K and available K in the rice rape rotation as affected by different treatments Treatment Total K (g/kg) 0-5cm 5-15cm Initial value in N 180 P 90 K 90 (CK) 19.5 a 19.4 a N 120 P 90 K 90 (R) 22.2 a 21.7 a N 150 P 90 K 90 (R) 22.7 a 21.8 a N 180 P 90 K 90 (R) 23.5 a 22.2 a N 210 P 90 K 90 (R) 24.9 a 22.5 a N 180 P 90 K 60 (R) 22.3 a 20.2 a N 180 P 90 K 0 (R) 22.7 a 19.3 a N 180 P 0 K 90 (R) 23.4 a 21.0 a Treatment Available K (mg/kg) 0-5cm 5-15cm Initial value in N 180 P 90 K 90 (CK) d a N 120 P 90 K 90 (R) a ab N 150 P 90 K 90 (R) a abc N 180 P 90 K 90 (R) a abc N 210 P 90 K 90 (R) cd bc N 180 P 90 K 60 (R) abc bc N 180 P 90 K 0 (R) bcd bc N 180 P 0 K 90 (R) a c Available K - sodium tetraphenyl-boron method

36 Soil organic matter in the rice rape rotation as affected by different treatments Treatment Soil OM (g/kg) 0-5cm 5-15cm Initial value in N 180 P 90 K 90 (CK) 24.5 c 15.9 c N 120 P 90 K 90 (R) 30.2 b 16.3 b N 150 P 90 K 90 (R) 30.9 ab 17.2 b N 180 P 90 K 90 (R) 44.0 a 24.8 ab N 210 P 90 K 90 (R) 48.8 a 29.2 a N 180 P 90 K 60 (R) 45.3 ab 23.7 ab N 180 P 90 K 0 (R) 46.4 a 28.6 a N 180 P 0 K 90 (R) 38.3 ab 19.6 b

37 Conclusions 1. K contained in straw is the highest among N, P, K and fast available to crops, especially in paddy rice field, while release of N and P from crop residues is much slower than K. 2. There is no competition for N between crops and soil microorganisms when crop residues are surface mulched, while the competition does exist when it is incorporated into soil within the first 40 d.

38 Summary 3. Crop residue returns to soil can help cut down significant amounts of fertilizer input while maintaining the similar yield levels as conventional cultivation. 4. Crop residue return resulted in accumulation of N, P and K and soil OM compared to the CK, and accumulation is mainly at the top 0-5 cm, but reduction occurs below 5 cm. 5. All K treatments reduced soil available K; Rice-rape rotation accumulated more soil K than rice-wheat rotation.

39 ACKNOWLEDGEMENT Sincere thanks to Ministry of Agriculture, Sichuan Department of Science and Technology and International Plant Nutrition Institute (IPNI) for their financial support.