Impact Assessment for Agriculture
Preface

The Impact Assessment and Applications Section (IAAS) of Climatology and Agrometeorology Division (CAD) regularly issue this monthly/bulletin which will provide users such as food security managers, economic policy makers, agricultural statisticians and agricultural extension officials with qualitative information on the current and potential effects of climate and weather variability on rainfed crops, particularly rice and corn. This bulletin, entitled “Climate Impact Assessment for Agriculture in the Philippines”, represents a method for converting meteorological data into economic information that can be used as supplement to information from other available sources.

For example, an agricultural statistician or economist involved in crop production and yield forecast problems can combine the assessment with analysis from area survey results, reports on the occurrence of pests and diseases, farmers’ reports and other data sources.

The impact assessments are based on agroclimatic indices derived from historical rainfall data recorded for the period 1951 to the present. The indices, expressed in raw values percent of normals and percentile ranks, together with real time meteorological data (monthly rainfall, in percent of normal), percent of normal cumulative rainfall, as well as the occurrence of significant event such as typhoons, floods and droughts are the tools used in the assessment of crop performance. Crop reports from PAGASA field stations are also helpful.


The narrative impact assessment included in the bulletin depicts the regional performance of upland, 1st lowland and 2nd lowland palay; and dry and wet season corn crops, depending on the period or the season. Tabulated values of normal rainfall and generalized monsoon and yield moisture indices are provided for ready reference. Spatial analysis of rainfall, percent of normal rainfall and the generalized monsoon indices in percentile ranks are also presented on maps to help users visualize any unusual weather occurring during the period. The generalized monsoon indices in particular, are drought indicators; hence, the tables (see Appendices) together with the threshold values can be used in assessing drought impact, if there are any. It also helps assess any probable crop failure.

It is hoped therefore that this bulletin would help provide the decision-makers, planners and economist with timely and reliable early warning/information on climatic impact including the potential for subsistence food shortfalls, thereby enabling them to plan alternate cropping, if possible, food assistance strategies/mitigation measures to reduce the adverse impact of climate and eventually improve disaster preparedness.

Impact assessment for other principal crops such as sugarcane and coconut, for energy and for water resources management, are from time to time will be included in the forthcoming issues of this bulletin.


The IAAS of CAD will appreciate suggestions/comments from end-users and interested parties for the improvement of this bulletin.

Definition of Terms
The Generalized Monsoon Index (GMI) helps determine the performance of the rains during the season and serves as a good indicator of potential irrigation supplies. It is a tool used to assess rainfed crops.

The GMI for the southwest monsoon (GMIsw) in an area during June to September is defined as follows:
GMIsw = W6P6 + W7P7 + W8P8 + W9P9

The GMI for the northeast monsoon (GMIne) in an area during October to January is defined as:
GMIne = W10P10 + W11P11 + W12P12 + W1P1

where:

W = weight coefficient of monthly rainfall for the season;
P = rainfall amount in the ith month
(i = 1 for January, 2 = for February, etc.)

The Yield Moisture Index (YMI) is a simple index that helps the users assess agroclimatic crop conditions during the crop season. The YMI for a particular crop is defined as follows:
n YMI =  [Pi Ki] i

where:

i = crop stage (1 = planting/transplanting,
2 = vegetative, 3 = flowering, 4 = maturity, etc.)
n = total no. of crop stages;
P = rainfall during the ith crop stage; and
K = appropriate crop coefficient for the ith crop stage.

Tentatively, the threshold values of categories of indices for interpretation being adopted for both YMI and GMI are as follows:


PERCINTELE RANK INTERPRETATION
> 80 Potential for Flood Damage
41 - 80 Near normal to above-normal crop condition
21 - 40 Moderate drought impact with reduced yield
11 - 20 Drought impact with major yield losses
< 10 Severe drought impact with crop failure and potential food shortages

REGIONS

Any farming activities related to rice and corn crops could not possibly be done because of insufficient moisture that is still prevalent across the region.
Dry weather continued as rice and other crops were completed over Cagayan Valley provinces.
Because of sufficient moisture available during the month, land preparation could have possibly been done in some parts of the region.
Harvesting of early-planted wet season corn has just begun in the eastern part of the region particularly in Casiguran; good to normal yield is expected because the crops experienced adequate moisture from planting to maturity.
Harvesting of early-planted wet season corn commences in most parts of the region; near normal-to-normal yield is anticipated because the crops experienced good weather and adequate moisture during their critical stage of growth and development. In Infanta, land preparation pertaining to planting of dry-season corn might be hampered due to inadequate amount of moisture available during the month.
Less moisture available during the month favored the newly harvested late-planted lowland 2nd palay now on its drying stage.
Harvesting of early-planted wet season corn has just started; near normal to normal yield is expected in Camarines Norte. In contrast, below normal yield is anticipated in the remaining parts of the region because the crops suffered from moisture stress during their vegetative stage. Meanwhile, sufficient moisture supply in Daet favored land preparation and planting of dry season corn.
Warm weather condition is still prevalent across the region, which allows the farmers to continue threshing and drying their newly harvested palay.
Harvesting of early-planted wet season corn has begun across the region; below normal yield is expected due to moisture stress experienced by the crops during their vegetative stage.
Harvesting of early-planted wet-season corn has now started all over the region; near normal-to-normal yield is anticipated because the crops experienced favorable conditions during reproductive stage of growth and development. Sufficient moisture available during the month favored land preparation and planting of dry season corn in Catarman.
Although rains accumulated during the month is above normal; drying of newly harvested late-planted lowland palay is still in progress in Zamboanga del Norte.
Below normal yield is expected to the newly harvested lowland 2nd palay, now on its drying stage, because of insufficient moisture experienced by the crops during their critical stage of growth and development.
Because of rains that occurred almost every day over the region, threshing and sun drying activities for the newly harvested late-planted lowland palay might have been adversely affected.
Insufficient moisture is still experienced across the region; thus, any farming activities pertaining to rice and corn crops could not possibly be done.
Harvesting of early-planted wet season corn has just begun across the region; near normal-to-normal yield is expected in most parts of the region during this season. In Butuan, however, the crops suffered moisture deficiency during grain filling stage of growth and development; hence, below normal yield is anticipated.

Meanwhile, land preparation and planting of dry season corn in most parts of the region is favored by sufficient moisture available during the month.
Threshing, sun drying, and stocking activities for the newly harvested late-planted lowland 2nd palay is currently in progress. Warm and dry weather conditions favored these activities.

Tropical Cyclone

No Active Tropical Cyclone

Actual Rainfall and Potential Evapotranspiration

Stations

For Particulars, please contact:

THELMA A. CINCO


Impact Assessment and Applications Section (IAAS)

Climatology and Agrometeorology Division (CAD)

PAGASA-DOST

Telefax No.: 434-58-82