Blogs 1 and 2 from May and June were rather complicated discussions of remote sensing imagery (focusing mostly on CERES images of these pistachio demo fields) and why the red (dry) to blue (wet) colorized image scale doesn't always remain constant from one image event to the next.  

BOTTOM LINE: for any given image, the color separation across the field of red to blue is always showing the true relative drier to wetter areas of the field on that date.  So many different colors across the block means the water status of the trees is quite variable.  You want 90% of the field to be green and blue.  BUT depending on the spread of canopy temperature (hottest to coolest areas) over the field on a given date some trees that showed up as green the month before might show up as yellow for the current month – even though the actual canopy temperature in degrees and a ground-based pressure bomb stem water potential (SWP) measured on the same trees are the same for both images.  Both images provide valuable information for that date – especially on field uniformity – but for an absolute verification of the degree of real tree stress, you need additional ground data.  Using this data, we verified that all fields were successfully winter/spring recharged with sufficient root zone soil moisture.  So for this BLOG we are looking at the combined data snapshot for our fields from 6/19/2020.

PRESSURE BOMB COMPARISON ACROSS ALL FIELDS

   

The above figure for 2020 shows that the non-saline Eastside and Westside fields are closer than they were for 2019.  As of June, the semi-saline Mid Salt site is about -2 bars more SWP stress than the non-saline fields and the saline HiSalt site is about -4 bars more stress.  This is NOT for lack of water but the result of the additional salt-caused osmotic resistance to water uptake.

NON-SALINE EASTSIDE FIELD

AERIAL IMAGERY:  This makes for good feeling as the fields are nearly all blue and green in all the fields, and we have -10 to -11 bars SWP in the west and SE fields (numbers in white) – so we are good to go!  But wait, we have a -15 bar SWP in the NE field, which indicates stress.  This was not obvious from looking at the trees and this field was irrigated with almost exactly the same amount of water as the other fields

TREE STRESS:  Using the tree as the continuous integrated moisture sensor is somewhat possible using a dendrometer that measures the real-time daily shrink/swell and growth of the tree.  The Phytech company is helping us do that by generating this average growth information in the below figure over 3 trees instrumented with dendrometers:

This is exactly the pattern that you want to see – steadily increasing growth running 15-30 microns/day over the spring and early summer.  From Mid-June to July 17 these trees averaged 6000 microns (6 mm) additional radial growth.  That's a 12 mm, or almost ½ inch increase in trunk diameter.  The blue bars indicate the timing and duration of irrigation of this high frequency double-line drip system.

So what about the -15 bar SWP stress we measured on the NE block?  We are fortunate to have 3 dendrometers on this block also which show a similar steady growth increase as the west 80 acres, but the slope is a little less so we only get 4000 microns increased growth (10-20/day) instead of the 6000 we have in the west 80 acres. This would confirm a bit more water stress in this block but not a big deal.

SOIL MOISTURE:

The ROOTZONE SUM chart below from the Jain Logic monitoring system using a Sentek Drill & Drop capacitance probe that measures soil moisture to a depth of 46 inches shows that the total root zone soil moisture has increased about 10% since the start of May.  The numbers on the left access are the sum of the percent soil moisture measured by each sensor placed every 4 inches.  If these numbers were absolutely accurate, it would mean that this Nord Series fine sandy loam soil would hold 42% water (5.0”/ft) at field capacity, which is impossibly high.  The correct number is about 28%, 3.4 inches/foot as measured by a neutron probe.  But the good news is that the trends in increased and decreased water content are very real and dependable.  So the infiltration chart (below right) is an accurate 

indicator of how deep water penetrates (dark blue columns) every irrigation.  This shows that the water only went to 46” a total of four times over 3 months, so there is virtually no deep percolation lost below the root zone.

NON-SALINE WESTSIDE FIELD

AERIAL IMAGERY:  Okay, this picture makes me feel a little more stressed than the Eastside CERES image – less blue and more yellow and red.  The SWP (numbers in white) are only -1 to -1.5 bars more negative (stressed) then the eastside SWP and this block did receive about 1.4 inch less water since 5/16 than the Eastside.  This is also a 300 acre block with ½ mile rows N to S with only 2 hose runs of ¼ mile each that appear to show weak pressure and water delivery in the middle and at the N and S sides of this block.

TREE STRESS:  Unfortunately, cell phone/web reception at this field is not good and only a little of the Phytech dendrometers data came through.  However, the 4 days data show as good of growth as the best Eastside block.

SOIL MOISTURE:  We have two sites in this field with instrumentation.  The NO COVER site below is 80 rows east of the west edge of the field with the soil classed as a Cerrini sandy loam.  The soil at this site is sandier than the Eastside field. The irrigation system is a single-line drip with four 1 gallon/hr drippers per tree.  Irrigation is typically a 24 hr set every other day starting in June.  The Root Zone Sum chart shows a fairly steady water content, but the Infiltration chart on the right shows that 5 straight irrigations in mid-June penetrated to 46”, indicating possible deep percolation earlier.

The COVER crop site is 30 rows from the eastern edge of the field and is a Calflax clay loam with a definitely higher water holding capacity than the Cerrini SL in the NO_COVER area.  This location and the NO_COVER location are in the same irrigation set, receiving water at the same time and duration – typically 24 hours.  But with a heavier soil, this site is showing water infiltrating nearly every irrigation as opposed to the sandy loam area just 50 rows to the east.  There is possibly a crack adjacent to a dripper that connects with the Sentek probe and pipes water down the side.  Of all the sites to have a failure in the Phytech dendrometers, this was possibly the worst one, and these trees did receive 1 inch less water over the last month than the Eastside.

SEMI-SALINE, SALINE LEMOORE FIELD

AERIAL IMAGERY:  As expected, the significant variability in canopy growth caused by excess salt and poor soil structure in this field produces the lowest and most variable Normalized Differential Vegetative Index (NDVI, left) and more WATER STRESS than in any other field.  Should more leaching have been done during the winter to further reduce root zone salt loads?  Perhaps the grower could have done more, but he applied 10 inches during the winter, which takes forever to penetrate in this saline-sodic Lethent silty clay loam, and his June 2020 SWP was less negative than June 2019.  This is square quarter-section field with a double-line high frequency automated drip system with two ¼ mile hose runs, running in 3 to 8 hour sets.  There is a distinct stress patter along the hose ends in the center and N and S borders of this field very similar to what we saw in the non-saline westside field with similar length of hose run.  These are all pressure compensated drip emitters and any time I have checked the pressure at the hose end it is >12 psi which should be sufficient for max flow.  So I'm guessing more emitters just get clogged and don't clean out during flushing.  Maybe it would help to increase filter station/booster pressure and flush hoses more often.  The grower used to run longer sets but that exacerbated the waterlogging problem.

TREE STRESS, SEMI-SALINE:  Even though there is definite canopy size, ET and yield reduction in the best semi-saline area of this block compared to our non-saline fields, there was still excellent growth recorded by the Phytech dendrometers from May to July.  In fact, the three trees with dendrometers in the NE area (D05) of this block have put on an average 10,000 microns (10 mm) additional radial growth.  That's a 20 mm, or ¾  inch increase in trunk diameter – the highest growth rate of all our monitoring sites even with extra stress from the salt!  Must be the seaweed extract Bart uses, hmmm.

TREE STRESS, SALINE:  This severely affected saline area in the south central part of the block surprised us last year with about half the growth of the D05 Area.  But this year has had essentially ZERO growth

SOIL MOISTURE, SEMI-SALINE:  The second highest total Root Zone Summed water content is this area – reflecting a soil texture finer than any of the non-saline problem fields and very slow drainage through the profile. The deepest penetration during an irrigation is only 18”.  The impact of this anoxia, waterlogging, has just as much negative impact on pistachio growth as does the higher salinity.

SOIL MOISTURE, SALINE:  The highest total Root Zone Summed water content is in this area (D03) of the field.  Frequently prone to ponding many trees have died here.  The deepest recorded irrigation penetration for any 3 to 8 hour event is 6”.  Installing an automated WiseCon irrigation system to run very short sets as often as daily has been the best strategy the grower found to reduce anaerobic conditions in the root zone and improve tree growth.

PRESSURE BOMB COMPARISON ACROSS ALL FIELDS

 The above figure for 2020 shows that the non-saline Eastside and Westside fields are closer than they were for 2019.  As of June, the semi-saline Mid Salt site is about -2 bars more SWP stress than the non-saline fields and the saline HiSalt site is about -4 bars more stress.  I can't say why, but as of July 23, the SWP for the MidSalt and HiSalt sites showed a virtually non-stressed value of -12 bars, the same as the Eastside Low Salt field.  The additional osmotic stress from the salt should cause an SWP that is at least -2 bars more stress than the non-saline field.

NON-SALINE EASTSIDE FIELD

AERIAL IMAGERY:  
The green to red image on the left indicates the volume and vigor of the canopy foliage as a Normalized Differential Vegetative Index (NDVI).  The right image shows the relative water stress across the orchard as calculated using the infrared canopy temperature.  The Demo monitoring is mostly for the western 80 acres in this image and the relative non-stressed SWP of about -12 bars makes sense with the mostly blue and green shown in this CERES water stress canopy temperature image.  However, we have a -17 bar SWP in the NE field and mostly yellow and red in the CERES image, which indicates stress.  This was not obvious from looking at the trees and this field was irrigated with almost exactly the same amount of water as the other fields.

TREE STRESS:  Using the tree as the continuous integrated moisture sensor is somewhat possible using a dendrometer that measures the real-time daily shrink/swell and growth of the tree.  The Phytech company is helping us do that by generating this average growth information in the below figure over three trees instrumented with dendrometers:

This is exactly the pattern that you want to see, up to mid-July – steadily increasing growth running 15-30 microns/day over the spring and early summer.  From Mid-June to July 17 these trees averaged 6000 microns (6 mm) additional radial growth.  That's a 12 mm, or almost ½ inch increase in trunk diameter.  The blue bars indicate the timing and duration of irrigation of this high frequency double-line drip system.  But from the end of July all growth ceases – probably due to the carbohydrate demand from the filling nuts.  You would still like to see a little growth but the good news is that the daily shrink/swell (shown by the daily high and low in the chart) is in the non-stressed range of 30-40 microns.

So what about the -17 bar SWP stress we measured on the NE block?  We are fortunate to have 3 dendrometers on this block also which show a similar steady growth increase through July, as we did with the west 80 acres, but the slope is a little less and erratic compared to the west 80 acres. This would confirm a bit more water stress in this block and as of August 1 the growth stalls out like the 80 acres, but as of August 5 some positive growth restarts – indicating either less stress or maybe a lighter crop load, which is consistent with visual observation in the field.

SOIL MOISTURE:

The ROOTZONE SUM chart below from the Jain Logic monitoring system using a Sentek Drill & Drop capacitance probe that measures soil moisture to a depth of 46 inches shows that the total root zone soil moisture has increased about 10% since the start of May.  The numbers on the left access are the sum of the percent soil moisture measured by each sensor placed every 4 inches.  If these numbers were absolutely accurate, it would mean that this Nord Series fine sandy loam soil would hold 42% water (5.0”/ft) at field capacity, which is impossibly high.  The correct number is about 28%, 3.4 inches/foot as measured by a neutron probe.  But the good news is that the trends in increased and decreased water content are very real and dependable.  So the infiltration chart (below right) is an accurate indicator of how deep water penetrates (dark blue columns) every irrigation.  This shows that the water only went to 46” one time over the last month, so there is virtually no deep percolation lost below the root zone.

NON-SALINE WESTSIDE FIELD

AERIAL IMAGERY:  Okay, this picture makes me feel a little more stressed than the Eastside CERES image – less blue and more yellow and red – especially around the edges and middle of the field at the ends of the hoses.  The SWP (numbers in white) are -1 to -2 bars more negative (stressed) then the eastside SWP but both blocks received almost the same irrigation (8.8 and 9.1”).  However, there is more windrun and higher ETo (potential evapotranspiration) across the westside Pleasant Valley area near Coalinga. This is also a 300-acre block with ½ mile rows N to S with only 2 hose runs of ¼ mile each that appear to show weak pressure and water delivery in the middle and at the N and S sides of this block.

TREE STRESS:  Unfortunately, cell phone/web reception at this field is not good and only a little of the Phytech dendrometers data came through.  However, the 4 days data show as good of growth as the best Eastside block but a higher amount of daily shrink/swell of the trunk.  This indicates that the tree has more stress on it moving the water up from the soil and out the leaf to meet ET during the day.  This could be due to the higher ETo of the Pleasant Valley area.

SOIL MOISTURE:  We have two sites in this field with instrumentation.  The NO COVER site below is 80 rows east of the west edge of the field with the soil classed as a Cerrini sandy loam.  The soil at this site is sandier than the Eastside field. The irrigation system is a single-line drip with four 1 gallon/hr drippers per tree.  Irrigation is typically a 24 hr set every other day starting in June.  The Root Zone Sum chart shows a fairly steady water content.  The Infiltration chart on the right shows a couple irrigations in July-August penetrated to 46” – less than the 5 irrigations to 46” in June.

The COVER crop site (below) is 30 rows from the eastern edge of the field and is a Calflax clay loam with a definitely higher water holding capacity than the Cerrini SL in the NO_COVER area.  This location and the NO_COVER location are in the same irrigation set, receiving water at the same time and duration – typically 24 hours.  But with a heavier soil, this site is showing water infiltrating nearly every irrigation as opposed to the sandy loam area just 50 rows to the east.  There is possibly a crack adjacent to a dripper that connects with the Sentek probe and pipes water down the side.  That said, this field now has the most negative SWP of all sites, averaging -13.5 bars, and with potentially the largest crop on the trees in the last 4 years and the hot wind that blows through Pleasant Valley, the grower is concerned about sufficient water for the nuts.  Therefore, starting July 24 (as you can see in the infiltration chart on the right) he has fired up another filter station running with canal water to irrigate the entire field (designed as a two set system) at one time – running for 6 days straight, off one day and then back on. Of all the sites to have a failure in the Phytech dendrometers, this is possibly the worst one.  Calculated flowrate for this 17x19 foot spacing with 4, 1 gph netafim button emitters/tree = 0.48 inches/day.

SEMI-SALINE, SALINE LEMOORE FIELD

AERIAL IMAGERY:  As expected, the significant variability in canopy growth caused by excess salt and poor soil structure in this field produces the lowest and most variable Normalized Differential Vegetative Index (NDVI, left) and usually more WATER STRESS than in any other field.  Should more leaching have been done during the winter to further reduce root zone salt loads?  Perhaps the grower could have done more, but he applied 10 inches during the winter, which takes forever to penetrate in this saline-sodic Lethent silty clay loam, and his June 2020 SWP was less negative than June 2019 and now the July 2019 shows even less stress than June.  This is square quarter-section field with a double-line high frequency automated drip system with two ¼ mile hose runs, running in 3 to 8 hour sets.  There is a distinct stress pattern along the hose ends in the center and N and S borders of this field very similar to what we saw in the non-saline westside field with similar lengths of hose run.  These are all pressure compensated drip emitters and any time I have checked the pressure at the hose end it is >12 psi which should be sufficient for max flow.  So I'm guessing more emitters just get clogged and don't clean out during flushing.  Maybe it would help to increase filter station/booster pressure and flush hoses more often.  The grower used to run longer sets but that exacerbated the waterlogging problem.

TREE STRESS, SEMI-SALINE:  Even though there is definite canopy size, ET and yield reduction in the best semi-saline area of this block compared to our non-saline fields, there was still excellent growth recorded by the Phytech dendrometers from May to July.  In fact, the three trees with dendrometers in the NE area (D05) of this block put on an average 10,000 microns (10 mm) additional radial growth.  That's a 20 mm, or ¾  inch increase in trunk diameter – the highest growth rate of all our monitoring sites even with extra stress from the salt!  Must be the seaweed extract this grower uses, hmmm.  That growth has slowed way down for July-August, but it has not stalled out – indicating minimal stress problems.

TREE STRESS, SALINE:  This severely affected saline area in the south central part of the block surprised us last year with about half the growth of the D05 Area.  Nevertheless, this year it has had essentially ZERO growth all season and even shows slight shrinkage for this July-August.  The shrink/swell change over 24 hours is also the largest of any site – measuring about 60-70 microns.

SOIL MOISTURE, SEMI-SALINE:  The second highest total Root Zone Summed water content is this area – reflecting a soil texture finer than any of the non-saline problem fields and very slow drainage through the profile. The deepest penetration during an irrigation is only 18”.  The impact of this anoxia, waterlogging, has just as much negative impact on pistachio growth as does the higher salinity.  Still, the trees need the water and this grower has increased hours per irrigation, while still allowing enough off time for at least some reoxygenation of the rootzone.

SOIL MOISTURE, SALINE:  The highest total Root Zone Summed water content is in this area (D03) of the field.  Frequently prone to ponding many trees have died here.  The deepest recorded irrigation penetration for any 3 to 8 hour event is 6”.  Installing an automated WiseCon irrigation system to run very short sets as often as daily has been the best strategy the grower found to reduce anaerobic conditions in the root zone and improve tree growth.

PRESSURE BOMB COMPARISON ACROSS ALL FIELDS

The above figure for 2020 shows that the non-saline Eastside and Westside fields are closer than they were for 2019 until the end of August.  At this time, the non-saline east field showed the greatest stress at -14 bars and even more stress after harvest (10/2) at -16 bars.  This field has been deficit irrigated due to infiltration and disease issues, receiving about 4 inches less water than the other fields since May.  I can't say why, but from 7/23 – 8/31, the SWP for the MidSalt and HiSalt sites showed the same non-stressed value of -12 bars.  The additional osmotic stress from the hi-salt area should cause an SWP that is about -2 bars more stress than the mid-salt area and non-saline eastside and westside.  Good irrigation scheduling and high frequency pulsed irrigation are helping this saline field.

IRRIGATION AND SOIL MOISTURE COMPARISON ACROSS ALL FIELDS

We have in-hose flowmeters at the exact location of every monitoring site in each of the 3 fields recording actual irrigation inches run through that hose.  The cumulative irrigation for each site is shown in the above chart along with the calculated ET using the Goldhamer crop coefficients (Kc) for pistachio and the Stratford CIMIS station.  As you can see, all sites received less water than the calculated ET.  Does this mean that every site was deficit irrigated and stressed more than it should have been?  Not necessarily – look again at the 2020 SWP chart and you can see that for nearly all the season the SWP was between -12 to -14 bars.  This indeed is mild stress indicating some deficit in water status but the CERES imagery and Phytech MDS also showed minimal tree stress for most of the season.

For all of these mature orchards, except for the really bad soil in the Lemoore High Salinity site, we have excellent available soil moisture storage and rooting to 6 feet.  The below chart shows the summed available inches to this depth over the season.  The Lemoore HiSalt site shows nearly double the stored water of the Westside NoCvr site because of a high clay content and poor structure in this sodic Lethent silty clay compared to the well-drained and aerated Cerrini sandy loam at the NoCvr site.

The below table now takes the cumulative irrigation over the season and adds in the season end (10/2, here) depletion of stored soil moisture from the highest storage point earlier in the season.  Depending on the site, this depletion was as little as 2.4 inches to about 6 inches.  Adding these depletions back into applied water puts us real close to the calculated 46” of Goldhamer ET for the Westside Cvr and NoCvr.  The Eastside Low Salt is now 40.3” and the Lemoore MidSalt and HiSalt sites with less canopy are the lowest, as expected, with 39.9 and 34.3”.  It is probably correct to say that the Eastside field had more deficit irrigation than desirable given the amount of yellow and red stress colors appeared in the CERES images over the season and have a final SWP of -16 on 10/2.

NON-SALINE EASTSIDE FIELD

AERIAL IMAGERY: 
The green to red image on the left indicates the volume and vigor of the canopy foliage as a Normalized Differential Vegetative Index (NDVI).  The right image shows the relative water stress across the orchard as calculated using the infrared canopy temperature.  The Demo monitoring is mostly for the western 80 acres in these images.  Compare the  10/8 post-harvest to the 8/31 pre-harvest image.  The amount of red-yellow stressed acreage increased by 30-50% over the harvest cutoff with minimal irrigation.  But if you look closely at the SWP, which were actually taken 10/2, for the west 80 acres and the SE 40 acres these remained almost the same at around -14 to -16 bars – mild stress.  However, these monitoring sites were chosen because the trees looked a bit better than average for the orchard.  These images confirm that these trees are on good dirt with a better than average water holding capacity compared to the rest of the orchard and they still show blue to green while the rest of the orchard is yellow-red.  However, the NE field has turned uniformly yellow-red – including the monitoring site which registered a very stressed SWP of -24 bars.  Why we see the very high stress on the NE field compared to the other two is a mystery.  All three fields are irrigated on the same schedule and receive virtually the same amount of irrigation.

The original CERES flyover date was set for Friday 10/2 to match the field data collection, but the smoke from the scattered fires across California had blown down to the southern SJV and was too thick on that day to do good imagery.  We obtained this 10/8 image as part of another project, but there is no imagery for the 4 westside non-saline and saline monitoring sites (2 fields).

TREE STRESS:  Using the tree and its larger root system as continuous integrated moisture monitor obviously gives you a more comprehensive picture than the small sphere of influence you get with a tensiometer, Watermark block or capacitance probe.  Stem water potential (SWP, the first chart in this BLOG) using a bagged leaf or wrapping a leaf with a wet rag for 15 seconds before picking is the industry standard for tree stress.  This is a good snapshot indicator of internal water stress right then but can be misleading without a knowledge of the real-time trend in tree stress.  There are different sensors out there now trying to do real-time tracking of sap flow, leaf stomatal conductance and internal osmotic tension in the tree sap.  These measurements are different from a straight pressure chamber SWP but closely related.  The problem with most of these sensors is maintaining stable readings and getting a true average for the whole tree over time. For this Pistachio Irrigation Monitoring/Scheduling Demo we are using a dendrometer that measures the real-time daily shrink/swell and growth of the tree trunk.  This device is less prone to placement and instrument error than other the commercial sensors mentioned above. The Phytech Company is helping us by supplying their dendrometers attached to three trees and real-time web-based reporting system that tracks the average shrinkage during the day and swelling at night – MAXIMUM DAILY SHRINK/SWELL, MDS, as an indicator of water stress, and average growth over time. 

This is exactly the pattern that you want to see, up to mid-July – steadily increasing growth running 15-30 microns/day over the spring and early summer.  From Mid-June to July 17 these trees averaged 6000 microns (6 mm) additional radial growth.  That's a 12 mm, or almost ½ inch increase in trunk diameter.  The blue bars indicate the timing and duration of irrigation of this high frequency double-line drip system.  But from the end of July there is very little growth – probably due to the carbohydrate demand from the filling nuts.  You would still like to see a little more growth than shown but the good news is that the daily shrink/swell (shown by the daily high and low in the chart and numbers at the bottom) is in the non-stressed range of 30-40 microns.

Notice the flat line starting 9/6.  That's when we removed the dendrometers from the trees so they wouldn't be damaged by the shakers.  They were reinstalled 10/7 (below chart).  Notice that the MDS is almost the same as the end of August running about 30-40 microns even though the average SWP was -16 on 10/3.  But the real-time irrigation monitoring (blue bars) shows they kicked up the irrigation to 6 hours/day on 10/9&10.  The CERES flyover occurred 10/8, just before these irrigations.

We also have the same Phytech system on the NE 40 acres block as we do with the west 80 acres.  So what about the    -24 bar SWP stress we measured on the NE block on 10/3 and all the yellow-red showing in the CERES image from 10/8?  Fortunately, we got the dendrometers back on the NE trees 10/2, which showed an MDS of 65 microns.  MDS for 10/3 (coinciding with the -24 bar SWP measurement) was 90 microns, but the very sharp peak means there may have been a hiccup in the reading and more like 50 or 60 microns is the reality.  From 10/4 on the MDS shows 20-40 microns – no stress.  A -24 bar SWP should cause an MDS of closer to 150 microns!  I have no explanation for this discrepancy.

JAIN LOGIC/SENTEK CAPACITANCE SOIL MOISTURE:

The ROOTZONE SUM chart below from the Jain Logic monitoring system using a Sentek Drill & Drop capacitance probe that measures soil moisture to a depth of 46 inches shows that the total root zone soil moisture has fallen off about 25% during harvest cutoff.  The numbers on the Y-axis in the bottom left chart are the sum of the percent soil moisture measured by each sensor placed every 4 inches.  If these numbers were absolutely accurate, it would mean that this Nord Series fine sandy loam soil would hold 42% water by volume (5.0”/ft) at field capacity, which is impossibly high.  The correct number is about 28%, 3.4 inches/foot (about 2” available) as measured by a neutron probe.  But the good news is that the trends in increased and decreased water content are very real and dependable.  Therefore, the infiltration chart (top left) is an accurate indicator of how deep water penetrates (dark blue columns) every irrigation.  This shows that the water only went to 30” over the last month, so there is no deep percolation lost below the root zone.  The capacitance probe appears to have stopped working on 10/3.  The Jain Logic estimate of total applied water is generated by a pressure sensor in the drip hose then multiplying the hours with pressure on by the system flowrate to get the applied inches.  But right now this is only 26.8” compared to the 35.4” we have measured because this does not account for the 5” of flood water applied and a couple inches applied before May 1.

WESTSIDE NON-SALINE

AERIAL IMAGERY:  Unavailable due to excessive smoke in the air.

PLANT STRESS

Unfortunately, the two Phytech systems in the Cover and Non-Cover crop monitoring sites in this 310 acre field have not been working for the last 2 months.  They should be back on-line soon.  The excellent average SWP of -12 to -13 bars was no surprise given the water scheduled to this block.

JAIN LOGIC/SENTEK CAPACITANCE SOIL MOISTURE

We have two sites in this field with instrumentation.  The NO COVER site below is 80 rows east of the west edge of the field with the soil classed as a Cerrini sandy loam.  The soil at this site is sandier than the Eastside field. The irrigation system is a single-line drip with four 1 gallon/hr drippers per 16 x 19 foot tree spacing.  Irrigation was typically a 24 hr set every other day starting in June.  With a second new filter station on-line for the field the grower ran two 72 hour sets back to back the third week of July to max out his rootzone storage.  The below Infiltration chart (top left) shows a 96 hour set starting 9/21 to recover soil moisture lost during the harvest cutoff for the first shake. The recharge makes it all the way to 46”. Irrigation is cutoff the morning of 9/25 and the 2^nd shake happens 10/1.  The soil moisture storage chart (bottom left) shows a recharge and subsequent depletion of about 100 mm from 9/21 to 10/5 – about 4 inches.  But wait a minute – this system has an application rate of 0.52 inches/day and it only ran 4 days, so that's 2.08”.  The trick here is knowing the subbing volume of the drip pattern.  The system application rate of 0.52”/day is for the whole acreage – 19 feet across the row, but if the drip pattern only subs across say 35-50% of the rootzone then the 0.52”/day becomes a 1 to 1.5 inch/day of actual wetting by the capacitance probe.  Likewise, if the ET = 0.3”/day, then that becomes a depletion of 0.6 to 0.9”/day in the wetted rootzone.

The COVER crop site (below) is 30 rows from the eastern edge of the field and is a Calflax clay loam with a definitely higher water holding capacity than the Cerrini SL in the NO_COVER area.  This location and the NO_COVER location are in the same irrigation set, receiving water at the same time and duration – typically 24 hours for a normal set.  But with a heavier soil, this site appears to have a greater zone of subbing than the Cerrini SL.  However, the recharge and the subsequent water use for the same 96 hour set as shown above is only shown to be about 25-30 mm at this site – barely 1” depth – not even the full 2” per system design.  However, the infiltration chart (top left below) still shows water penetrating to the 46”.  This shows the problem of calibration for this kind of technology.  The trends shown in both charts are nearly identical – indicating good recharge and subsequent water use by the trees in between first and second shake, but the actual numbers at the Calflax site are not correct.

LEMOORE SEMI-SALINE AND SALINE

AERIAL IMAGERY:  Excessive smoke prevented the scheduled CERES flyover for 10/2.

PLANT STRESS:  The salt burn is quite apparent at both sites, but at the highly saline site the burn has consumed about 25-40% of the leaf while at the semi-saline site maybe <10% of leaf area.  The burned tissue plus the reduced canopy oddly works to make the SWP less negative (less stressful) then it would be due to the increased osmotic resistance to water uptake under these highly saline conditions.  This means that the average SWP at the HiSalt site is barely more stressed at -14.1 bars compared to the MidSalt location averaging -13.4 bars.

But looking at the Phytech dendrometers shows an average Maximum Daily Shrink/swell (MDS) of 30-35 microns for the semi-saline D05 site compared to an average 40-50 microns MDS for the Saline D03 site – basically a 30% higher stress due to increased salts at this site.

SOIL MOISTURE, SEMI-SALINE:  The second highest total Root Zone Summed water content is this area – reflecting a soil texture finer than any of the non-saline problem fields and very slow drainage through the profile. The deepest penetration during an irrigation is only 12-14”.  The impact of anoxia (waterlogging) has just as much negative impact on pistachio growth as does drought and high salinity.  So the grower uses 3 hour pulsed irrigation once or twice daily with this high-tech automated Wise-Con irrigation system in an attempt to reduce water-logging while recharging some of the soil moisture lost during harvest cutoff.

SOIL MOISTURE, SALINE:  The highest total Root Zone Summed water content is in this area (D03) of the field.  Frequently prone to ponding many trees have died here.  The deepest recorded irrigation penetration for any 3 to 8 hour event is 14”.  Installing an automated WiseCon irrigation system to run very short sets as often as daily has been the best strategy the grower found to reduce anaerobic conditions in the root zone and improve tree growth. Irrigation was cutoff for harvest on 9/4 and restarted for 5 days on 9/18.