Yield, soil water and economic benefits to a long a fallow. Yvette Oliver and Rob Sands 26 Feb 2013

Transcription

1 Yield, soil water and economic benefits to a long a fallow Yvette Oliver and Rob Sands 26 Feb 2013

2 Long fallow wheat Long and Short fallow Store summer + winter + summer rainfall Use water stored + GSR Nov May Nov May Nov Summer fallow continuous wheat Store summer rainfall Use water stored + GSR Store summer rainfall Use water stored + GSR Nov May Nov May Nov

3 Why farmers are using long chemical Strategically fallow Weed and disease control option Limited break crop options or have no sheep Drought risk - for increased stored soil water near sowing Potential for additional soil Nitrogen Opportunistic - Forced by season Couldn t sow crops in time Poor season, crop not going to produce a break even yield High weed burden

4 Yield benefits of a long fallow Yield benefits of long fallow ~ 0-2 t/ha Yield benefit from fallow depends on Amount of stored water Growing season rainfall Nitrogen added from fallow Fallow weed control, disease break etc Early sowing opportunity Amount of stored soil water depends on.. Summer rainfall amount, timing and pattern Soil Plant Available Water Capacity (PAWC) Management of Weeds

5 How much rainfall can I store? Average Rainfall (mm) ( ) Rainfall Dalwallinu Perenjori Merredin Out of season - October to April January-April Growing season - May to September Average stored soil water (mm) at sowing Soil type Dalwallinu Perenjori Merredin Soil PAWC Continuous wheat 18 month fallow Continuous wheat 18 month fallow Continuous wheat Clay-Loam Loam Good sand Shallow or poor sands month fallow

6 Yield benefits of long fallow Average continuous wheat (CW) yield (t/ha), Increased yield from a fallow (when a yield benefit occurred) and % years a benefit occurred in last 100 years Soil type Dalwallinu Perenjori Merredin CW yield (t/ha) Yield benefit % years CW yield (t/ha) Yield benefit % years CW yield (t/ha) Clay-Loam % Loam % Good sand % Shallow or poor sands % Yield benefit % years (CW yield = 07* Yield potential, yield benefit only counted when >50kg/ha

7 Yield benefits of long fallow Average continuous wheat (CW) yield (t/ha), Increased yield from a fallow (when a yield benefit occurred) and % years a benefit occurred in last 100 years Soil type Dalwallinu Perenjori Merredin CW yield (t/ha) Yield benefit % years CW yield (t/ha) Yield benefit % years CW yield (t/ha) Clay-Loam % % Loam % % Good sand % % Shallow or poor sands % % Yield benefit % years (CW yield = 07* Yield potential, yield benefit only counted when >50kg/ha

8 Yield benefits of long fallow Average continuous wheat (CW) yield (t/ha), Increased yield from a fallow (when a yield benefit occurred) and % years a benefit occurred in last 100 years Soil type Dalwallinu Perenjori Merredin CW yield Yield benefit % years CW yield Yield benefit % years CW yield Yield benefit % years (t/ha) (t/ha) (t/ha) Clay-Loam % % % Loam % % % Good sand % % % Shallow or poor sands % % % (CW yield = 07* Yield potential, yield benefit only counted when >50kg/ha

9 % yield differnce from a fallow Yield increase, GSR and summer rainfall 350% 350% 300% Loam Perenjori 300% 250% Loam Dalwallinu 250% 200% Loam Merredin 200% 150% 150% 100% 100% 50% 50% 0% -50% May-Sept Rainfall (mm) 0% -50% Jan-April Rainfall GSR < 210 mm of wheat after fallow greater benefits from fallow Low summer rainfall < 110 mm possible benefit to fallowing

10 Yield difference (t/ha) Yield benefit from long fallow at Perenjori 6 out of last 10 years on a good sand/loam with 9/10 with GSR < 210mm Yield increase when More stored soil water after fallow AND Less than 210mm Growing Season Rainfall Higher stored soil water after fallow BUT Average Growing Season Rainfall (2005) No Yield difference when No difference in stored soil water from high summer rainfall (> 110mm in 2001, 2006 and 2008 )

11 Yield difference (t/ha) Yield benefit from long fallow at Dalwallinu 3 out of last 10 years on a good sand/loam but 5/10 with GSR < 210mm Yield increase when More stored soil water after fallow (Summer rainfall <110mm) AND Growing Season Rainfall < 210mm (2002 and 2007) In 2006, GSR < 210mm but summer rainfall >110mm (pattern of rainfall important)

12 Best chance of benefit from fallow Good soil high Plant available water capacity which can store the additional water Areas with low GSR (drier regions) and drought seasons Areas with low summer rainfall Full profile at start of fallow = don t fallow Onto Rob for Economics and other benefits of a long fallow

13 Fallow Economics Rob Sands Yield Boost Frequency Opportunity Cost Timeliness of Sowing Variable Costs Fixed Costs The Alternatives

14 Opportunity Cost? $/ha Year Good Year Average Poor Year Yield Price (Farm Gate) Income Costs Profit Fallow Cost Opportunity Cost Yield Boost Needed (at $250)

15 Example Calculations Perenjori Clay Loam Perenjori CW yield (t/ha) Yield benefit % years %

16 Fallow Profitability in Rotations Assumptions Base Yield Income Costs $/ha Profit Farm Gate Fert Herbicide Other variable Fixed $/ha $/t Wheat 1.92 $250 $70 $50 $110 $95 $199 $81 Barley 2.02 $240 $70 $50 $110 $95 $159 $79 Grain Legume 0.60 $300 $25 $32 $110 $95 -$82 -$137 Fallow $30 $95 -$125 -$125 DSE $/DSE $/DSE $/DSE Pasture 2 $50 $27 $72 -$26 -$13

17 Yi eld Boost x years i n 10 using Probability yr average Pasture/w/b/pasture/w/b $103 $103 $103 Grain legume/ w/w/b/b $117 $117 $117 Fallow/w/w/b/b $101 $101 $101 Fallow/w/w/b/b with yield boost on 20% of area With Wheat Price = $250 Farm Gate Price Yield benefit from fallow 0.82 t/ha occurs 50% of years $41/ha less cost of fallow for additional yield of $7/ha = $34/ha $101 $134 $117

18 Time of Sowing Penalties Timeliness of sowing Penalty % / day Days of seeding? Dry seed Sown wet Av. Timing discount Income loss Pasture 1.0% % $0 Grain Legume 1.0% % $22.48 Fallow 1.0% % $11.24 Assume weeds are controlled well enough on Pasture, Grain Legume or Fallow to Dry Seed

19 Extra Costs to Achieve Yield Boost Extra Cost/t Units/t $/unit $/t N 20 $1.20 $24 P 3 $3.00 $9 Harvest 1 $10.00 $10 TOTAL $43

20 Fallow Vs Pasture Normal year After fallow year Over 10 years Average of 10 yrs Benefit/ cost over pasture -$2 $31 $140 $14 Timeliness -$11 -$11 -$110 -$11 Savings in weed control $3 $3 $30 $3 Net Cashflow -$10 $19 $58 $6 Net benefit Equiv to $35 NPV Av benefit is a 6% increase in profit

21 Fallow Vs Grain Legumes Normal year After fallow year Over 10 years Average of 10 yrs Benefit/ cost over grain legume -$17 $17 -$5 -$0.50 Timeliness $11 $11 $112 $11.20 Savings in weed control $3 $3 $30 $3.00 Net Cashflow -$2 $29 $137 $13.70 Net benefit NPV $87 Av benefit 13% increase in average profit

22 Average Rotational Profit $/ha Rotation Assumptions Profit Profit adjusted for Pasture/w/b/pasture/w/b Grain legume/w/w/b/b Fallow/w/w/b/b Pasture has minimal legume content, N Cost Saving of $20 N Cost saving of $40 for first wheat? 20% of area grown on fallow Timeliness Yield boost Low crop herbicide $103 $103 $103 $103 $117 $95 $95 $95 $101 $89 $105 $108

23 Fallow Profitability in Rotations Average Rotation Profit $/ha Soil type Dalwallinu Perenjori Merredin Pastur e /w/b Grain Legume /w/w/b/b Fallow /w/w/b/b Pasture /w/b? Grain Legume /w/w/b/b Fallow /w/w/b/b Pasture /w/b 2.5 DSE/ha Grain Legume /w/w/b/b Fallow /w/w/b/b Clay-Loam Loam Good Sand Shallow or poor sands

24 Key messages Economic benefits over other rotations can be achieved with fallow on heavier soil types at Perenjori and Merredin using a set rotation of one fallow every five years. Fallow is likely to be more profitable than a legume rotation in Perenjori on loams and good sands unless you can achieve better than district average yields for the grain legumes grown. The opportunity cost in the year of fallow is critical, so don t fallow in a year that has an above average yield potential. The years with the best yield potential are years with good stored moisture at seeding and early sowing opportunities.

25 Questions? Rob Sand Yvette Oliver