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News and information from UC Cooperative Extension about alfalfa and forage production.
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Comments:
by John Harris
on May 14, 2015 at 11:38 AM
Thank you for a much-needed, biological and agronomic perspective on alfalfa's use of water. You make a strong case that alfalfa is unfairly maligned. If California would move toward a true, market-based system for water sourcing and distribution, much of the criticism would be muted. Water would be used in a more economically efficient way, which likely would favor crop production.
Reply by Daniel H Putnam
on May 14, 2015 at 12:49 PM
Thanks for your comment, John.  
Dan
by Bryan Bingham
on May 17, 2015 at 9:58 AM
Very interesting article. What I wonder is if you perhaps should consider the rest of the livestock business when comparing product efficiency. Unlike, say, almonds or lettuce, hay isn't consumed directly. Cattle uses a lot more water than just the hay, so perhaps milk, cheese, or meat should the correct products to compare against. Of course, as far as farmers are concerned, they just deliver a crop and your data makes a lot of sense.
Reply by Daniel H Putnam
on May 17, 2015 at 11:34 AM
Byran;  
Good points. There are definitely inefficiencies (with all crops) by the time it gets to the table. This issue of final product efficiency is interesting but is tricky business - what do you consider to be the important measurement? - pounds of product per unit water? Nutritional or monetary value (to whom-the farmer or consumer?) Calories per unit water? (In that case, suagarbeet would be the hands-down winner, and we should all eat plenty of sugar?) Protein per unit water? Staple foods like milk, wheat or rice, vs. specialty (luxury?) foods like almonds and wine?? Lettuce, though consumed directly is great stuff, love it! But nutritional value compared with milk? Kale, maybe. Since consumers demand a wide range of foods, those are what growers grow, responding to markets.  
If we applied a water-use efficiency metric, we probably wouldn't grow lettuce - depending upon how you calculated it!  
 
One key point of that exercise is that innately food production require lots of water - something we should all be aware of. By the way, the economic value to CA of the livestock-forage system (as a %) is approximately equal to its water footprint.
by Bill Wilson
on May 17, 2015 at 2:26 PM
AS usual a very good article that has application here in Central Texas.
by Ja Robb
on May 19, 2015 at 6:51 AM
Appreciated the insights in your article, found it via a summary in an electronic magazine.
Reply by Daniel H Putnam
on May 19, 2015 at 10:13 AM
Thanks for the comments, Bill and Ja Robb
by joe janak
on May 19, 2015 at 9:27 AM
Very applicable in Texas. Agree totally.  
 
My only concern is too much water/rain on heavy soils.  
We received 32 inches since planting in October. Lost about 100 % stand in low spots; 65% of 24 acres. Need to drain better but land is too flat. I'm working with UofG Agronomist in testing/selecting cultivars that can withstand excess rainfall.  
Would like to speak with Bill Wilson; 361-649-2243
Reply by Daniel H Putnam
on May 19, 2015 at 10:12 AM
Very good point, Joe.  
Alfalfa seedlings especially are subject to flooding - both pythium and phytopthora root rots and other diseases, and just plain lack of oxygen. One of the reasons alfalfa isn't widely grown in the South.  
We've had periodic losses of alfalfa in the Sacramento Valley in the past- back when we actually had rain.  
In some areas, you could consider re-planting, which some of our growers have done after a stand loss.  
We're jealous about your rainfall!
by Larry Farwell
on May 19, 2015 at 10:39 AM
Good information for farmer and urban dweller alike. Two points -with the subsidence and overdraft in California it is important to note that continued mining of groundwater is not in agriculture's long-term interest and that fields irrigated with mined groundwater should be fallowed. And, the picture of an alfalfa field irrigated with low-volume emitters is lovely but might be misleading. What percentage of CA alfalfa fields are flood and sprinkler irrigated? Thanks.
Reply by Daniel H Putnam
on May 19, 2015 at 10:55 AM
Larry;  
Many thanks for your comments. CA Alfalfa fields are likely at least 82% surface systems (check flood, bedded), sprinklers 15% (pivots, moveable pipe and wheel lines) and buried drip a few percentages - but increasing. Groundwater recharge is an important benefit of surface systems - we are working hard on subsurface drip and sprinkler systems which have advantages in matching water with crop need - however, both groundwater recharge and wildlife habitat are improved with surface systems. Salt management too. Surface systems have the advantage of very low energy requirements, but have important limitations which are well understood. We recommend a more flexible approach which uses all systems when appropriate. One shouldn't have a 'knee jerk' view that is: 'why doesn't everyone use one system (e.g. drip)" Each system has its appropriate uses.  
 
A great discussion of groundwater issue (mining) can be seen in Thomas Harter's great talk in Long Beach at the Alfalfa Symposium last year: http://lecture.ucanr.org/Mediasite/Play/fb650167098643ac8d629cab207dd9121d  
 
Groundwater pressures are immense and we need to understand them better. However, some are easily refilled, but others not.  
 
No matter which system is used (surface, sprinklers or drip) we need to learn how to manage them better, and how to respond to low water years. Each is subject to improvement.
by Aamir
on May 20, 2015 at 11:47 AM
Really a mind changing article' removing misconception that alfalfa is a crop for areas with abundant agricultural water. To Cater with drought like situation in Pakistan' sorghum may be the best choice among summer forages while alfalfa has the potential to provide nutritious forage in May-June when there is a severe deficiency of forage for ruminants. after reading the biological characters of alfalfa' I must say Sorghum and alfalfa are panacea for undernourished ruminants in Pakistan.
by Daniel H Putnam
on May 23, 2015 at 6:56 AM
Thanks for your comments, Aamir. Actually, it's interesting that in regions of the world with lots of rainfall, there is not much alfalfa, as in tropical areas.
by Jamshaid Ahmad
on June 17, 2015 at 10:40 AM
Hello Dan  
Very interesting article regarding biological and agronomic prospective on alfalfa’s use of water. We have drought condition in our area in Punjab (Pakistan) and cannot irrigate the alfalfa field for last two months. But only I inch of rainfall after two month the alfalfa crop regrowth very well. Hopefully from next month rainy season starts and take advantage of higher yield from alfalfa crop.
by Hector Mendez
on July 14, 2015 at 7:57 AM
Very good article, which was informative and timely. But I question the yield numbers cited: (10-12 tons/acre) normal and up to 14 tons/acre.  
An earlier report "Alfalfa Production Systems in California" by D. Putnam, C. summers and S. Orloff 12/2007 cited average yields of 7.0 to 7.5 tons/acre. Our local statistics are similar.  
Perhaps I am missing a conversion factor?
Reply by Daniel H Putnam
on July 14, 2015 at 5:25 PM
Hi Hector;  
The 'normal' yields I quoted were specifically for that variety trial in Fresno County under high salinity, which were in the 10-12 t/a range (e.g. normal for our variety trials in this area which tend to be higher than county averages). It is true that yields can reach 14 (or even 16) t/a in the San Joaquin Valley and Imperial Valley- and we have seen this on grower's fields, especially with drip. But you are quite right the AVERAGE yields for this region are closer to 8 tons/acre. Statewide in CA, average yields are actually closer to 7-7.5 tons/acre due to lower production in the Intermountain regions (3-4 cut, short-season area). Actual yields on growers fields in depleted stands under lower management, can be near 4-5 tons, but approach 14 tons/acre under top management in long seasoned environments. Within a region, yields can vary widely due to management and age of stand. So you are correct to challenge this, but what I quoted was accurate. Thanks for the comments!
by John Kramer
on July 14, 2016 at 1:07 PM
Many years ago Tom Lockhart told me that alfalfa will use readily-available nitrogen in irrigation water preferentially over fixing it from the atmosphere. Do you know if that is the case? I know alfalfa is commonly used in reclamation projects for nutrient management, but a common criticism of that crop choice is the well-known fact that legumes help to nitrogenate the soil. People ask me why are you nitrogenating the soil in a nutrient management plan supposedly designed to consume waste nitrogen?
Reply by Daniel H Putnam
on July 15, 2016 at 12:44 PM
John;  
Excellent question and comment.  
 
Yes, alfalfa will take up excess N in irrigation water (or manure or municipal wastewater). It's also true that legumes produce nearly all of their own N for their growth, especially alfalfa and they provide N to subsequent crops. So both are true.  
 
However, with alfalfa, and with many legumes, when excess N is available in the soil solution, it will take up that N preferentially, and nodulation will go way down, so they really don't 'fix' much N under those conditions. They become 'lazy' and take it from the soil solution, fertilizers, irrigation water, or manures or wasetwater.  
 
That's why alfalfa is such a great crop to 'scrub' N from soil water, since it's uptake level is so high (300-900 lbs N/acre per year). It's higher than corn, and because it's cut 5-9 times, one can apply every cutting.  
 
Alfalfa has been used to 'scrub' excess N from train fertilizer spillage, municipal wastes, and dairy wastes. It's deep roots assist in helping to draw these waters up from lower down. If the irrigation is adequate (and not over-irrigated), it can be used to mitigate excess N in water if necessary. So your friend Tom Lockhart is correct.  
 
Cheers,  
 
Dan
 
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